Task 2 - What do we know about COVID-19 risk factors?

Which are the main risk factors?

where E is the expectation of the outbreak probabilities ; thus , we consider a probability distribution of branching processes . This way Risk x = Risk ( C , θ , R loc ) , which means that the risk depends on the efficacy of Chinese control measures that influence the cumulative case number C , the connectivity between the index and destination areas θ , and the local reproduction number R loc . The main question we aim to get insight into is how this risk depends on these three determining factors .

The number of imported cases i is given by a random variable X , where X∼Binom ( C , θ ) . The outbreak risk in a country x is then estimated as Riskx = E [ 1−zX ] , where E is the expectation of the outbreak probabilities ; thus , we consider a probability distribution of branching processes . This way Riskx = Risk ( C , θ , Rloc ) , which means that the risk depends on the efficacy of Chinese control measures that influence the cumulative case number C , the connectivity between the index and destination areas θ , and the local reproduction number Rloc . The main question we aim to get insight into is how this risk depends on these three determining factors .

In general , main risks of bias in the 50 cross - sectional studies were the lack of use of reliable and valid instruments to measure mental health outcomes ( high risk of bias in 22 % of the studies ) and selection bias ( 12 % ) . The main sources of bias across the seven cohort studies were selection bias ( 43 % ) and inadequate follow - up of the cohorts ( 29 % ) . Main sources of bias of the two uncontrolled before - after studies were bias in selection of participants , and bias in outcome measurement . The case - control and the systematic review identified did not present serious risks of bias . Results of the risk of bias assessment are provided in Online Appendix 3 .

To the best of our knowledge , this is the first systematic review and meta - analysis to develop an informed understanding of the prevalence , severity and mortality of COPD patients diagnosed with COVID - 19 . We provide an updated report in relation to smokers ( 32 ) . Our main outcomes show that the prevalence of COPD in COVID - 19 patients was low , but that the risk of severity ( 63 % ) and mortality ( 60 % ) were high , which indicates COPD patients with confirmed COVID - 19 are at a greater risk of severe complications and death .

Cluster four has the lowest risk among the four clusters . ̅ = 1 . 20 indicates the lowest level of virus transmission , while 1 ̅ = 0 . 65 % and 2 ̅ = 0 . 51 % are 62 . 5 % and 50 . 0 % higher than the average respectively . Their epidemic spread is very light , and is more easily suppressed . The diagnosis rate , ̅ = 0 . 38 , is the lowest , which may have the main reason that the demand for diagnosis level is not high .

Does smoking increase risk for COVID-19?

It is essential to consider the potential risk of morbidity and possible mortality for each MS patient , who may be infected with SARS - CoV - 2 and develops COVID - 19 . The individual ' s risk profile is multifactorial ; their DMT and consequent immune response is one of the factors . Other aspects to consider , when assessing a respiratory viral infection include : smoking practices ( increased cigarette smoking increases risk ) ; ambulatory status ( less mobility increases risk , especially if the patient is in a wheelchair ) ; age ( increasing age increases risk ) ; weight ( increasing weight impacts on ambulation and respiratory function ) ; underlying respiratory illnesses , such as asthma or COPD . Also , the frequency of necessary attendance at a hospital or healthcare facility for laboratory or MRI testing , but also for infusions may place the patient at a higher risk of exposure . In the context of these factors the health care professionals should weigh the potential risks of SARS - CoV - 1 exposure and manage their DMT accordingly . Visits for MS care should preferably be done by telemedicine or phone .

In summary , active cigarette smoking and COPD up - regulate ACE - 2 expression in lower airways , which in part may explain the increased risk of severe COVID - 19 in these sub - populations .

Introduction : Coronavirus disease 2019 ( COVID - 19 ) is a respiratory infection caused by the severe acute respiratory syndrome coronavirus2 ( SARSCoV - 2 ) . This virus uses the angiotensin converting enzyme II ( ACE2 ) as the cellular entry receptor to infect the lower respiratory tract . Because individuals with chronic obstructive pulmonary disease ( COPD ) are at increased risk of severe COVID19 , we determined whether ACE2 expression in the lower airways was related to COPD and cigarette smoking . Methods : Using RNAseq , we determined gene expression levels in bronchial epithelia obtained from cytologic brushings of 6th to 8th generation airways in individuals with and without COPD . We externally validated these results from two additional independent cohorts , which used microarray technologies to measure gene expression levels from 6th to 12th generation airways . Results : In the discovery cohort ( n = 42 participants ) , we found that ACE2 expression levels were increased by 48 % in the airways of COPD compared with non - COPD subjects ( COPD = 2 . 52 ( 0 . 66 ) log2 counts per million reads ( CPM ) versus non - COPD = 1 . 70 ( 0 . 51 ) CPM , p = . 000762 ) . There was a significant inverse relationship between ACE2 gene expression and FEV1 % of predicted ( r = negative 0 . 24 ; p = 0 . 035 ) . Current smoking also significantly increased ACE2 expression levels compared with never smokers ( never current smokers = 2 . 77 ( 90 . 91 ) CPM versus smokers = 1 . 78 ( 0 . 39 ) CPM , p = 0 . 024 ) . These findings were replicated in the two external cohorts . Conclusions : ACE2 expression in lower airways is increased in patients with COPD and with current smoking . These data suggest that these two subgroups are at increased risk of serious COVID19 infection and highlight the importance of smoking cessation in reducing the risk .

As COPD patients are at an increased risk of severe outcomes if they became infected with COVID - 19 , it is recommended that patients and clinicians establish effective plans for ensuring prevention , such as using tele - medicine to ensure that COPD receive the best care ( 56 , 57 ) . We strongly advocate public awareness campaigns concentrating on ways to achieve smoking cessation among smokers , and it is possible that an improvement in cessation rates will help to reduce the spread of SARS - CoV - 2 . Future studies should investigate the mechanisms between COPD , smoking and COVID - 19 infection .

The factors that mediate susceptibility to SARS - CoV - 2 infections are poorly understood . We speculate that the increased expression of ACE2 in the lungs of smokers could partially contribute to the severe cases of COVID - 19 that have been observed in this population . In support of this hypothesis , mice that were engineered to express high levels of human ACE2 succumbed to infections with a related coronavirus more quickly than mice that expressed low levels of human ACE2 9 . Nonetheless , the relevance of increased ACE2 expression as a driver of disease susceptibility in humans or for SARS - CoV - 2 remains to be demonstrated . Chronic smokers may exhibit a number of co - morbidities , including emphysema , atherosclerosis , and decreased immune function 86 , that are also likely to affect COVID - 19 progression . While the effects of smoking can last for years , smoking cessation causes an improvement in lung function and an overall decrease in disease burden 86 . Interestingly , quitting smoking also leads to a normalization of respiratory epithelial architecture 87 , a decrease in hyperplasia 88 , and a downregulation of ACE2 levels . Thus , for multiple reasons , smoking cessation could eventually lessen the risks associated with SARS - CoV - 2 infections .

Is a pre-existing pulmonary disease a risk factor for COVID-19?

Do co-infections increase risk for COVID-19?

Three levels of risk of infection are defined for contacts / co - exposed persons of a possible / confirmed COVID - 19 case ( Table ) . Co - exposed persons of a confirmed case are followed - up according to the same procedure as a moderate - / high - risk contact . The follow - up procedure for the contacts / co - exposed persons differs according to the evaluation of the level of risk of infection ( Table ) .

A . CC - BY - NC - ND 4 . 0 International license It is made available under a author / funder , who has granted medRxiv a license to display the preprint in perpetuity . The overall risk score can be used to compare practices . Moreover , as the number of days the health care worker is doing his or her regular job related to a COVID - 19 task , the risk of infection increases . The number of days can be scaled accordingly as exposure time .

There are not yet any clear models to guide risk predictions in patients infected with COVID - 19 . One report by the Centres for Disease Control in China provided numbers of patients and fatalities divided by age , and by comorbidities . However , there was no cross - tabulation of factors , and so it is not clear how many patients in each age group had each comorbdity , nor how the risks associated with those co - morbidities interact with each other 3 . There is one small series of 18 patients with cancer , which suggests higher risks of intubation or death , but it is so small it difficult to draw robust conclusions , and the authors ' conclusions have been criticised 4 . One other study suggests patients with a history of cancer have a higher risk of becoming infected with COVID . The data from CDC China have been used to simulate a population and then develop a risk model based on that simulated population 5 ; Although a useful step , it almost certainly leads to " double counting " of risk ( i . e . the increased risk of death in older patients and in those with hypertension is related , as hypertension is commoner in the elderly ) . Data from patients admitted to hospital show an increased risk of death in older patients 6 .

A meta - analysis 3 of clinical trial data including 4135 patients given anti - tumor necrosis factor ( TNF ) therapy found that the relative risk of developing an opportunistic infection was 2 · 05 ( 95 % CI 1 · 10 - 3 · 85 ) with anti - TNF therapy compared with placebo ; opportunistic infections included tuberculosis , herpes simplex infection , oral or oesophageal candidiasis , herpes zoster virus , cytomegalovirus , and Epstein - Barr virus . A pooled analysis of 2266 patients given adalimumab found that higher disease activity was associated with significantly increased risks of both serious and opportunistic infections at 1 year . 4 Furthermore , vedolizumab , a humanised monoclonal antibody with gut selectivity , has been associated with airway and bowel infections , although to a lesser extent than with anti - TNF drugs . 5 The risk of opportunistic infection seems to be increased in patients with inflammatory bowel disease who are older than 50 years and receiving immunosuppression . 6 , 7 As a result of this increased risk of opportunistic infections , inflammatory bowel disease guidelines suggest giving patients a viral screening before starting biologics . 8 In particular , the screening should include serology for hepatitis B virus , hepatitis C virus , HIV , and varicella zoster virus ( in patients without a clear history of previous infection or vaccination ) , and tuberculosis screening through a combination of clinical risk stratification , chest x - ray , and IFN - γ release assays . Additionally , an assessment of history of specific infections is suggested , including herpes simplex virus , varicella zoster virus , and tuberculosis , and of immunisation status . 3 Patients with inflammatory bowel disease might be at an increased risk of SARS - CoV - 2 infection , and the risk of a severe clinical course of COVID - 19 might be increased in individuals with chronic disease on immunomodulatory treatment . Furthermore , the risk of inducing clinical activation in individuals with asymptomatic SARS - CoV - 2 infection cannot be excluded . As such , we believe that current recommendations for screening before initiation of biologics should be updated ( at least temporarily ) to include testing for SARS - CoV - 2 . In view of the rapid spread of the COVID - 19 pandemic , we believe physicians should screen for COVID - 19 even if patients are asymptomatic or do not have a history of high - risk travel or contact . However , importantly , the exact method of such screening should be decided on the basis of local policy and available health - care resources .

Making appropriate treatment decisions with patients requires a careful balance of risks and benefits . When our treatments are accompanied by good quality evidence , we have good estimates of benefit and can consent with access to data on likely acute and long - term harms . The risk benefit ratio of treatment changes in the context of a pandemic . If the likelihood of serious infection increases or the likelihood of the outcome of that infection being more serious increases , then the risk may start to outweigh the If a patient has a 5 % risk of infection and 10 % risk of death from infection there may be a 0 . 5 % mortality through exposure and attendance for radiotherapy . If the patient is young and healthy with a 5 % risk of infection and 1 % risk of death , then there is 0 . 05 % mortality from COVID - 19 . The use of chemotherapy in combination with radiotherapy is likely to very significantly increase the risk of morbidity and mortality from synchronous COVID - 19 infection .

Does a respiratory or viral infection increase risk for COVID-19?

It is essential to consider the potential risk of morbidity and possible mortality for each MS patient , who may be infected with SARS - CoV - 2 and develops COVID - 19 . The individual ' s risk profile is multifactorial ; their DMT and consequent immune response is one of the factors . Other aspects to consider , when assessing a respiratory viral infection include : smoking practices ( increased cigarette smoking increases risk ) ; ambulatory status ( less mobility increases risk , especially if the patient is in a wheelchair ) ; age ( increasing age increases risk ) ; weight ( increasing weight impacts on ambulation and respiratory function ) ; underlying respiratory illnesses , such as asthma or COPD . Also , the frequency of necessary attendance at a hospital or healthcare facility for laboratory or MRI testing , but also for infusions may place the patient at a higher risk of exposure . In the context of these factors the health care professionals should weigh the potential risks of SARS - CoV - 1 exposure and manage their DMT accordingly . Visits for MS care should preferably be done by telemedicine or phone .

However , the effects of DPP4 inhibition on the immune response in patients with type 2 diabetes is controversial and not completely understood . A meta - analysis showed that upper respiratory tract infections does not increase significantly with DPP4 inhibitor treatment . When compared with placebo or active comparator treatment , risks of respiratory infection in for DPP4 inhibitors were all comparable [ 9 ] . Initiation of a DPP4 inhibitor was not associated with an increased risk of respiratory tract infections , On the contrary , anti - inflammatory and anti - adipogenic , effects have been associated with the use of DPP4 inhibitors and GLP - 1 receptor analogs [ 10 ] . Reduced macrophage infiltration directly via GLP - 1 dependent signaling and reduced insulin resistance and inflammation by regulating M1 / M2 macrophage polarization have been described with DPP4 inhibition and GLP - 1 activation . This brief overview wants to stimulate the discussion on the potential role of DPP4 in COVID - 19 - infected individuals with type 2 diabetes . It is unclear whether DPP4 inhibition or modulation should be the most appropriate strategy . However , DPP4 may represent a potential target for preventing and reducing the risk and the progression of the acute respiratory complications that type 2 diabetes may add to the COVID - 19 infection .

Chronic viral hepatitis does not appear to increase the risk of a severe course of COVID - 19 . 1 Use telemedicine / local laboratory testing for follow - up visits in patients under antiviral therapy , send follow - up - prescriptions by mail . Patients with non - alcoholic fatty liver disease ( NAFLD ) or steatohepatitis ( NASH ) may suffer from metabolic comorbidities such as diabetes , hypertension and obesity putting them at increased risk of a severe course of COVID - 19 .

The timing and decision to intubate patients with COVID - 19 should be made on a case - by - case basis . The threshold for intubation may be lower in COVID - 19 since use of high - flow nasal oxygen ( HFNO ) or non - invasive ventilation may potentially increase the risk of transmission to HCW [ 18 ] . Disease transmission risk of viral respiratory infections during intubation has been shown to be high [ 18 , 24 ] , and therefore early , controlled intubation may also increase the safety margin of intubation and by allowing adequate preparation time for this high - risk procedure . Airborne precautions should be applied throughout .

The most striking finding is that under a range of conditions , most cancer patients are at > 5 % risk of death if infected with COVID - 19 . It is notable that the 5 % is greater than or equal to the benefit from most adjuvant chemotherapy for adult solid tumours . Although we accept that exact negative impact of COVID - 19 in subgroups remains unclear , previous data during outbreaks of seasonal respiratory viral infections suggests that they are associated with an approximate doubling in risk . However , in contrast to outbreaks of seasonal infections , the majority of the population is expected to be infected with COVID - 19 over a short - time period ( 3 - 6 months ) , there is no pre - existing immunity or vaccine , and the case - fatality rate is approximately 5 fold higher . For those reasons , decision - making in seasonal viral outbreaks does not directly transfer to the COVID - 19 pandemic . Decisions about initiating or continuing cytotoxic chemotherapy in the context of a COVID pandemic need to be made carefully , and in light of the available data .

Are neonates at increased risk of COVID-19?

Since December 2019 , there has been an outbreak of novel coronavirus ( 2019 - nCoV ) infection in China . Two cases of neonates with positive 2019 - nCoV tests have been reported . Due to the immature immune system and the possibility of vertical transmission from mother to infant , neonates have become a high - risk group susceptible to 2019 - nCoV , which emphasize a close cooperation from both perinatal and neonatal pediatrics . In neonatal intensive care unit ( NICU ) , to prevent and control infection , there should be practical measures to ensure the optimal management of children potentially to be infected . According to the latest 2019 - nCoV national management plan and the actual situation , the Chinese Neonatal 2019 - nCoV expert working Group has put forward measures on the prevention and control of neonatal 2019 - nCoV infection .

In the period of COVID - 19 outbreak , routine prenatal examination was limited by traffic control and isolation policy in place , and hence pathological pregnancy can ' t be found timely , which may be the reasons for the high emergency caesarean delivery and general anaesthesia use in the COVID - 19 patients in this study . Although general anaesthesia would induce or exacerbate pulmonary complications in parturients 11 with COVID - 19 , the cesarean delivery under general anaesthesia is necessarily to be used for fetal distress , potential contraindication of intrathecal anaesthesia , as well as intrathecal anaesthesia failure . The rapid - sequence induction by using propofol , rocuronium and remifentanil was used in our COVID - 19 patients and the excellent maternal hemodynamic stability was noted . However , the possible risk of short - time neonatal depression and required short periods of mask ventilation or tactile stimulation of the neonate were found . However , in this study , either intravenous or inhalational induction was not difference in term of the safety of maternal and neonatal and the risk infection of medical staff . To avoid hemorrhage resulted from uterine atony , inhalational sevoflurane was switched into intravenous anaesthetics after umbilical cordligation . Notably , PPE increased the difficult in airway management and it was necessary for the use of visual laryngoscopes , and the supraglottic airway was considered as a remedy for failed tracheal intubation in emergency general anaesthesia 12 .

2019 novel coronavirus ( 2019 - nCoV ) infection has been spreading in China since December 2019 . Neonates are presumably the high - risk population susceptible to 2019 - nCoV due to immature immune function . The neonatal intensive care unit ( NICU ) should be prepared for 2019 - nCoV infections as far as possible . The emergency response plan enables the efficient response capability of NICU . During the epidemic of 2019 - nCoV , the emergency response plan for the NICU should be based on the actual situation , including diagnosis , isolation , and treatment , as well as available equipment and staffing , and take into account the psychosocial needs of the families and neonatal care staff .

BACKGROUND There is little information about the coronavirus disease 2019 ( Covid - 19 ) during pregnancy . This study aimed to determine the clinical features and the maternal and neonatal outcomes of pregnant women with Covid - 19 . METHODS In this retrospective analysis from five hospitals , we included pregnant women with Covid - 19 from January 1 to February 20 , 2020 . The primary composite endpoints were admission to an intensive care unit ( ICU ) , the use of mechanical ventilation , or death . Secondary endpoints included the clinical severity of Covid - 19 , neonatal mortality , admission to neonatal intensive care unit ( NICU ) , and the incidence of acute respiratory distress syndrome ( ARDS ) of pregnant women and newborns . RESULTS Thirty - three pregnant women with Covid - 19 and 28 newborns were identified . One ( 3 % ) pregnant woman needed the use of mechanical ventilation . No pregnant women admitted to the ICU . There were no moralities among pregnant women or newborns . The percentages of pregnant women with mild , moderate , and severe symptoms were 13 ( 39 . 4 % ) , 19 ( 57 . 6 % ) , and 1 ( 3 % ) . One ( 3 . 6 % ) newborn developed ARDS and was admitted to the NICU . The rate of perinatal transmission of SARS - CoV - 2 was 3 . 6 % . CONCLUSIONS This report suggests that pregnant women are not at increased risk for severe illness or mortality with Covid - 19 compared with the general population . The SARS - CoV - 2 infection during pregnancy might not be associated with as adverse obstetrical and neonatal outcomes that are seen with the severe acute respiratory syndrome coronavirus ( SARS - CoV ) and Middle East respiratory syndrome coronavirus ( MERS - CoV ) infection during pregnancy . ( Funded by the National Key Research and Development Program . )

In view of the above , the risk of the current COVID - 19 pandemic for conception is non - existent . On the other hand , the available published data on the potential maternal and neonatal outcomes from women infected with SARS - CoV - 2 during pregnancy are inconclusive . While there is a consensus as to the virtual lack of risk of SARS - CoV - 2 vertical mother - to - child transmission ( Schwartz and Graham , 2020 ) , the potential risk of maternal infection with SARS - CoV - 2 during pregnancy for the health status of newborns is a matter of debate . One study reported various kinds of health problems in nine out of ten neonates born to mothers with SARS - CoV - 2 pneumonia , leading to the death of one of them ( Zhu et al . , 2020 ) . On the other hand , another study reported the birth of nine normal children , without any health problems to mothers with laboratory - confirmed COVID - 19 ( Chen et al . , 2020 ) . In both studies , the vertical transmission of SARS - CoV - 2 infection from the mothers to the newborns was excluded . The differences between the neonatal outcomes reported in each of the two studies may be partly explained by the low number of cases analyzed . However , the clinical symptomatology of the mothers in the series reported by Zhu et al . ( 2020 ) appears to be more severe compared with those in the report by Chen et al . , ( 2020 ) . Consequently , the worse neonatal outcomes reported in the latter study may have been due to factors related to the mothers ' health status just before , and during , parturition , rather than to a specific cause related to SARS - CoV - 2 infection . Whatever the case , it seems prudent to try to avoid pregnancy as long as the risk of SARS - CoV - 2 infection remains high . It is of interest to note that despite the fact that viral infections can cause the same devastating effects on pregnancies resulting from spontaneous conception as on those resulting from ART , no government has recommended general contraception , as was the case with Zika virus .

Are pregnant women at increased risk of COVID-19?

In conclusion , our report showed pregnant women are also susceptible to SARS - CoV - 2 infection . SARS - CoV - 2 may increase health risks to both mothers and infants during pregnancy . Efforts should be taken to reduce the infection rate of SARS - CoV - 2 both in pregnant and perinatal period , and more intensive attention should be paid to pregnant patients .

The emergence of the epidemic raised concerns regarding pregnant women as high - risk individuals . The prevention and management of COVID - 19 in pregnant women and the possible risk of vertical transmission become the main concern ( 9 ) . This meta - analysis is the first study to achieve a comprehensive pattern of the COVID - 19 clinical features in pregnant women . We included seven studies with a total of 50 patients from China . The mean age of pregnant patients was 30 - year old and all were in third trimesters at the time of manifestation .

A review of pregnant women infected with COVID - 19 revealed that pregnant women are not at increased risk of poor outcomes when compared to the general adult population [ 47 ] , and there seems to be no evidence of vertical transmission of the SARS - CoV - 2 virus from mother to baby during birth or during breastfeeding at present [ 20 , 47 ] . All the women who gave birth with COVID - 19 had cesarean sections , so there is no data about vertical transmission for women who are infected earlier in the pregnancy or who deliver vaginally . More studies are clearly warranted to examine the potential impact of COVID - 19 on pregnancy .

In addition to children , pregnant women also represent a vulnerable population at risk for viral infections , with increased risk of complications in influenza , including the 2009 influenza H1N1 pandemic ( Siston et al . , 2010 ) , varicella virus , measles and the severe foetal consequences of Zika virus ( reviewed in ( Racicot and Mor , 2017 ) ) . Interestingly , and in line with the pattern of COVID - 19 producing milder symptoms in children , there is currently no evidence for increased risk of severe outcomes of COVID - 19 in pregnant women . We should note , though , that this evidence is based on limited data , while reports from SARS - CoV , MERS - CoV and from other respiratory infections suggest these conclusions are premature and pregnant women could be at risk of a severe course of COVID - 19 ( Rasmussen et al . , 2020 ) . If , however , pregnancy proves to provide some protection from disease severity , it could offer unique opportunities for the development of therapeutic solutions . It would also be essential to see whether COVID - 19 during pregnancy has longer - term implications for the offspring , similar to neurodevelopmental impacts of maternal influenza and other infections ( Meyer et al . , 2007 ) .

We report clinical data from nine pregnant women with laboratory - confirmed COVID - 19 pneumonia . The clinical characteristics of these patients with COVID - 19 infection during pregnancy were similar to those of non - pregnant adults with COVID - 19 infection , as previously reported . 2 None of the nine patients developed severe pneumonia or died , as of Feb 4 , 2020 . Notably , based on our findings in these nine patients , there is currently no evidence to s uggest that development of COVID - 19 pneumonia in the third trimester of pregnancy could lead to the occurrence of severe Pregnant women are particularly susceptible to respiratory pathogens and severe pneumonia , because they are at an immunosuppressive state , and physiological adaptive changes during pregnancy ( eg , diaphragm elevation , increased oxygen consumption , and oedema of respiratory tract mucosa ) can render them intolerant to hypoxia . For example , the 1918 influenza pandemic caused a mortality rate of 2 · 6 % in the overall population , but 37 % among pregnant women . 8 Pregnant women were reported to be at an increased risk of complications from the pandemic H1N1 2009 influenza virus infection , and were more than four times more likely to be admitted to hospital than the general population ( relative risk 4 · 3 [ 95 % CI 2 · 3 - 7 · 8 ] ) . 9 Wong and colleagues 10 also reported that around 50 % of pregnant women who developed SARS were admitted to the intensive care unit , around 33 % of pregnant women with SARS required mechanical ventilation , and the mortality rate was as high as 25 % for these women . In the current study , we treated nine pregnant women with COVID - 19 pneumonia in 11 days from Jan 20 to Jan 31 , 2020 . Considering that SARS - CoV - 2 has up to 85 % sequence similarity with SARS , [ 11 ] [ 12 ] [ 13 ] [ 14 ] although none of our patients developed severe pneumonia or died of COVID - 19 infection , we should be alert to the possibility that the disease course and prognosis of COVID - 19 pneumonia could follow the same trend as SARS in pregnant women . However , our obser vations are based on a small number of cases and the time between illness onset and delivery was short .

Is there any socio-economic factor associated with increased risk for COVID-19?

With COVID - 19 , we need to identify all possible animal sources and routes of transmission as they determine the persistence in animals ranging from infection to disease to being a reservoir . Accidental or continuous spill - over to human beings usually determines the length of exposure and consequent outbreaks . 5 Socio - economic and behavioural risk factors in various societies and geographic regions also play a critical role . Various risk reduction strategies at human , animal and environmental interface need to be studied for defining the high - risk situations .

There are not yet any clear models to guide risk predictions in patients infected with COVID - 19 . One report by the Centres for Disease Control in China provided numbers of patients and fatalities divided by age , and by comorbidities . However , there was no cross - tabulation of factors , and so it is not clear how many patients in each age group had each comorbdity , nor how the risks associated with those co - morbidities interact with each other 3 . There is one small series of 18 patients with cancer , which suggests higher risks of intubation or death , but it is so small it difficult to draw robust conclusions , and the authors ' conclusions have been criticised 4 . One other study suggests patients with a history of cancer have a higher risk of becoming infected with COVID . The data from CDC China have been used to simulate a population and then develop a risk model based on that simulated population 5 ; Although a useful step , it almost certainly leads to " double counting " of risk ( i . e . the increased risk of death in older patients and in those with hypertension is related , as hypertension is commoner in the elderly ) . Data from patients admitted to hospital show an increased risk of death in older patients 6 .

The direct association between COVID - 19 - attributable mortality and country - level economic status observed in this analysis is starkly counterintuitive . Prior global disease burden assessments have suggested that deaths from acute respiratory illness are typically higher in low - income settings due to multiple socio - demographic and economic risk factors 16 , 17 . Among observed COVID - 19 - attributable risk factors for disease severity and death , age over 65 years has been identified as a significant factor 4 , 18 , while it is inferred that LMICs which typically have a younger population structure would potentially experience fewer overall deaths . Another potential confounder was the time lag in deaths following detection of cases . We selected countries with at least 100 reported cases and adjusted for time since this sentinel event . After adjusting for country economic status , proportion of older population and aligning the epidemic trajectories of the highest hit countries , the intriguing observation of a significant association between BCG use and lower COVID - 19 - attributable mortality remained discernable .

Younger age was a risk factor for both PTSD 75 and burnout , 26 while female gender was associated with higher levels of PTSD in HCWs . 75 Feelings of social rejection or isolation , 63 and higher impact of the outbreak on daily life 72 increased the likelihood of developing PTSD , whereas lack of family and friends support were associated with burnout . 43 In addition , stigmatisation , 44 social rejection , 67 and lower levels of social support were identified as risk factors for stress . 83

However , any overestimation of the incidence of AKI may not have directly affected our investigation of AKI risk factors . We found that compared with non - AKI patients with COVID - 19 , older age , multiple pre - existing comorbidities , an increased white blood cell count , low lymphocyte count , and increased levels of PCT and CRP , were risk factors for AKI . The prevalence of several of . CC - BY - ND 4 . 0 International license It is made available under a author / funder , who has granted medRxiv a license to display the preprint in perpetuity .

Is there any behavioral factor associated with increased risk for COVID-19?

For behavioral responses , increases in anxiety levels , perceived risks and harms to body relative to SARS , and confusion about information reliability were significantly associated with higher probability of carrying out all recommended and avoidance behaviors during the outbreak ( Table 3 ) . For increases in frequencies of immediate handwashing behavior when returning home , the factor that exerted the largest impact was having received and read information brochures from the government , followed by having correct perceived efficacy of behaviors ( Table S3 ) . Higher perceived harm to body compared with SARS was the only factor with significant explanatory power for goggles purchase behavior . We found no evidence that perceptions and anxiety levels were associated with changes in frequencies of wearing face masks during the outbreak ( Table S3 ) .

There are not yet any clear models to guide risk predictions in patients infected with COVID - 19 . One report by the Centres for Disease Control in China provided numbers of patients and fatalities divided by age , and by comorbidities . However , there was no cross - tabulation of factors , and so it is not clear how many patients in each age group had each comorbdity , nor how the risks associated with those co - morbidities interact with each other 3 . There is one small series of 18 patients with cancer , which suggests higher risks of intubation or death , but it is so small it difficult to draw robust conclusions , and the authors ' conclusions have been criticised 4 . One other study suggests patients with a history of cancer have a higher risk of becoming infected with COVID . The data from CDC China have been used to simulate a population and then develop a risk model based on that simulated population 5 ; Although a useful step , it almost certainly leads to " double counting " of risk ( i . e . the increased risk of death in older patients and in those with hypertension is related , as hypertension is commoner in the elderly ) . Data from patients admitted to hospital show an increased risk of death in older patients 6 .

How could the risks of contact lens wear be further minimised to reduce any potential burden on hospital visits at this time ? The risk factors that result in CIEs and infectious keratitis are well understood . The relative risks of developing CIEs are summarised in the comprehensive review by Steele and Szczotka - Flynn , [ 11 ] and include nonmodifiable factors such as younger age ( 1 . 75 - 2 . 61x ) , higher prescription ( ≥5D ) ( 1 . 21−1 . 6x ) and history of a previous event ( 2 . 5 - 6 . 1x ) , along with modifiable risks such as overnight wear ( 2 . 5−7x ) , bacterial bioburden on the lens and lid margins ( 5−8x ) , and lens replacement schedule - reusable compared to daily disposable ( 12 . 5x ) . MK is associated with many similar factors , including overnight wear [ 13 , 105 , 106 ] , and for daily wear , poor lens and storage case hygiene , infrequent lens case replacement , exposure to water and smoking [ 109 , 110 ] . Risk factors for MK in daily disposable wearers are more frequent use , any overnight wear , less frequent handwashing , and smoking [ 111 ] . While it is not possible to change a non - modifiable risk factor such as the age of a patient , there are significant opportunities to address modifiable behaviours . Given the reduced incidence of CIEs in wearers of daily disposable lenses [ 99 , 100 ] , this form of lens wear seems ideal in a time of reduced clinical provision . Some patients hold supplies of both reusable and daily disposable contact lenses , with the latter normally used for sports or holidays . With appropriate practitioner discussion , a move to using daily disposable lenses could be recommended at the current time .

BACKGROUND : Middle East Respiratory Syndrome ( MERS ) is a respiratory disease caused by a novel coronavirus that was identified in 2012 in Saudi Arabia . It is associated with significant mortality and morbidity . We identified factors associated with the Middle East Respiratory Syndrome - Coronavirus ( MERS ‐ CoV ) infection among suspected cases presented with sign and symptoms of upper respiratory infection or exposure to the virus . We also looked at the impact of medication history on virus transmission . METHOD : We included subjects with suspected MERS - CoV infection and confirmed cases of MERS infection . Subjects were excluded if there were any missing data that prevent the final analysis . Descriptive statistics were used to report demographic data . Percentages and frequencies were used to summarize the categorical variables , while means and standard deviations were calculated for continuous variables . Logistic regression was used to assess the risk of MERS - CoV infection among the suspected cases . A value of p < 0 . 05 was considered statistically significant . RESULTS : A total of 16 , 189 suspected cases were identified , complete data were analyzed for 3154 to assess factors that are independently associated with MERS - CoV infection . MERS - CoV infection was associated with age ( adjusted odds ratio [ AOR ] = 1 . 06 ; 95 % CI [ 1 . 02 – 1 . 098 ] , P - value = 0 . 004 ) , male gender ( AOR = 1 . 617 ; 95 % CI [ 1 . 365 – 1 . 77 ] , P - value < 0 . 001 ) and diabetes ( AOR = 1 . 68 ; 95 % CI [ 1 . 346 – 1 . 848 ] , P - value = 0 . 002 . There was no significant association with the other comorbidities . Medication history was not associated with an increase or decrease the likelihood of the infection . CONCLUSIONS : MERS - Cov infection is more common in male , advanced age and diabetes . No medications were associated with an increase or decrease the likelihood of the infection . This is important to focus on screening and detection to this patient population .

The legal behaviors in using medical masks in public have been finally promulgated by the Vietnamese Government after 47 days since the WHO declared the Public Health Emergency of International Concern ( PHEIC ) due to the COVID - 19 pandemic . From a sample of 345 Vietnamese respondents aged from 15 to 47 years , this brief note found that the risk perception of COVID - 19 danger significantly increases the likelihood of wearing the medical masks . In addition , there is a weak evidence about the differences in age under the COVID - 19 outbreaks . More noticeably , those who use masks before COVID - 19 pandemic tend to maintain their behaviors . Our results offer the insightful into Vietnamese citizens responses in terms of using medical masks ; even the uses of this method are still controversial . Our results are robust by performing Exploratory Factor Analysis for five features and further regressions .

What is the basic reproductive number?

The optimal , with respect to the reported confirmed cases from the 11th of January 291 to the 10th of February value of the infected rate ( α ) was found to be ∼ 0 . 319 ( 90 % CI : 292 0 . 318 - 0 . 32 ) . This corresponds to a mean value of the basic reproduction numberR 0 ≈ 2 . 293 Finally , using the derived values of the parameters α , β , γ , we have run the SIRD author / funder , who has granted medRxiv a license to display the preprint in perpetuity .

What are the similarities and differences of COVID - 19 epidemiology in comparison with SARS and MERS ? What is the basic reproductive number ( R 0 ) , the real incubation period , and the morbidity and mortality rate ? Can COVID - 19 develop into an endemic or seasonal infectious disease , like the flu ?

In conclusion , the basic reproductive number of COVID - 19 , although is a precious variable to forecast the spreading potential of an infectious disease , is not the only factor to consider when estimating the burden of the epidemic . There is much more to known about this new infection : what is the transmission ability of asymptomatic carriers ? What is the proportion of infected cases missed at the tracing and control procedures ? Are the current strategies to prevent the spreading of the infection effective ? Global efforts are , therefore , needed to address all these questions .

According to the comparison chart of the average number of people infected with a single infection ( The basic reproduction number ) ( Figure 3 ) , we found that the basic reproduction number had a great impact on the spread of the epidemic . With the increase of basic reproduction number , the total number of infected people will be more and more , and the larger the basic reproduction number , the faster the disease will spread . We set the basic reproduction number in the range of 3 - 4 . 6 for simulation . It is found that when the basic reproduction number is 3 . 8 , the simulated curve ( yellow line ) is better close to the official confirmed number curve ( red line ) , that is to say , the real basic reproduction number in Wuhan should be 3 . 8 . However , some scholars put forward the basic reproduction number between ( 2 . 8 , 3 . 9 ) , and others put forward the basic reproduction number of 2 . 2 [ 3 ] . . CC - BY 4 . 0 International license It is made available under a is the author / funder , who has granted medRxiv a license to display the preprint in perpetuity .

The basic reproduction number is model - based , largely depends on the epidemiological setting , and is the most important parameter to determine intrinsic transmissibility . The early outbreak data largely follow exponential growth . Different models based on the clinical progression of the disease were devised to estimate the basic reproduction number . In the early stages of COVID - 19 , the pandemic doubled in size every 7 . 4 days , and the basic reproduction number was estimated to be 2 . 2 [ 7 ] . Another study estimated the basic reproduction number as ranging from 2 . 24 to 3 . 58 [ 11 ] . However , a deterministic compartmental model based on the likelihood and a model analysis showed that the control reproduction number may be as high as 6 . 47 [ 12 ] . The authors noted that this basic reproduction number was higher because the estimate accounts for 3 - 4 generations of viral transmission and intensive social contacts . The basic reproduction number estimated by the majority of studies ranges from 2 . 24 to 3 . 58 [ 13 ] , which is slightly higher than that of SARS .

What is the incubation period?

Among the collected data , the incubation periods of 483 confirmed patients can be estimated . Statistical results are shown in Fig . 3 and Tab . 1 . The estimated incubation periods for the 483 patients roughly follow the logarithm normal distribution , with a long right tail . Specifically , the 483 confirmed patients were with average estimated incubation periodτ D = 7 . 4 days , the mode was 4 days ( 50 out of the 483 cases ) and the median was 7 days ( 48 out of the 483 cases ) . About 55 % patients were with incubation periods lower than 7 days , while more than 92 % patients were lower than 14 days . About 7 . 45 % patients were overestimated with more than 14 days incubation periods .

Based on what is known about similar coronaviruses , the longest potential incubation period for COVID - 19 is thought to be 14 days from initial exposure [ 4 , 6 ] . The mean incubation period is 5 . 2 days ( 95 % CI 4 . 1 - 7 . 0 ) but can range from 2 to 14 days [ 4 , 20 , 43 ] . Co - infections occur in 22 - 33 % of patients and may be higher in critical patients [ 44 , 45 ] .

To contain the spread of COVID - 19 , several pertinent questions need to be addressed . What is the infect iousness of cases ? What are the settings and activities beyond family clusters where spread can occur ? What measures should be taken to improve surveillance and casedetection ? What measures can reduce disease spread ? To answer these questions , we report data for the first three clusters of COVID - 19 cases in Singapore , the epidemi ological and clinical investigations done to ascertain disease characteristics and exposure types , and summary statistics to characterise the incubation period of severe acute respiratory syndrome coronavirus 2 ( SARS - CoV - 2 ) and the serial interval between trans mission pairs . Our findings will be important for countries and cities to calibrate detection and response efforts during the ongoing epidemic .

These recommendations pertain to patients potentially infected with Covid - 19 , but with the extension of the epidemic beyond China and the relatively long asymptomatic incubation period of up to 14 days [ 4 ] , it will probably be increasingly difficult to identify these patients . Without intending to give rise to paranoia , several questions arise : what is the risk of transmission by asymptomatic patients during the incubation period ? Do these asymptomatic patients have virus present in their tears ? And for us ophthalmologists , is there a risk of viral transmission ?

The classic epidemic models are mainly based on the capacities of the virus to propagate in an environment without protection . The variables include disease incubation period , speed and strength of viral propagation while introducing some assumptions related to the slowdown barriers . However , reality could be a lot more complicated . For instance , COVID - 19 ' s incubation period varies from 1 to 14 days . What ' s more , to stop epidemic spread and reduce infections to lower levels is a concerted effort of both the government and the people . The strategies of dealing with the outbreak , the strength of government execution , how people react and respond to the measures are critical to the number of infections .

What are the modes of transmission?

What are the environmental factors?

a ) Environmental hygiene in medical sectors and personal hygiene of health care workers should be maintained [ 55 , 56 ] . b ) Contact tracing , strict isolation of actively ill patients and quarantine of close contacts should be implemented early [ 54 ] . c ) Training in the use of personal protective equipment protects the safety of HCWs [ 57 ] . d ) Establishing fever clinics , setting up designated hospital wards and SARS hospitals reduced human - to - human transmission [ 58 ] . e ) Education of the public on communicable diseases and what measures to take on a personal basis to prevent spread .

To be able to better interpret case fatality rates , more data are thus needed ( panel ) . First , the type and severity of organ failure : what are the real contributions of respiratory or cardiovascular failure ? How many patients died with isolated respiratory failure , in shock or with acute kidney injury or multiple organ failure ? Second , the actual process of death , including therapeutic limitation when present and the relative contributions of patient factors ( eg , age and comorbidities ) or environmental factors ( eg , lack of facilities , beds , personnel , or equipment ) . Last , the real contribution to death of SARS - CoV - 2 infection , because COVID - 19 can be an epiphenomenon in some patients .

We established a rule of environmental clearance and checking . The area and frequency of environmental clearance increased and the clearance was checked by ATP fluorescence assay randomly .

Taken together , the survival of the COVID - 19 virus in different environmental media , including water , PM , dust , and sewage under a variety of environmental parameters warrants systematic investigation immediately . Levels of infectious virus in environmental samples could be low , requiring high - sensitivity methods for precise quantitation of COVID - 19 virus to be developed . In the future , this novel coronavirus may also become a seasonal infectious virus . The occurrence , survival , and behavior of COVID - 19 virus in environmental compartments should be determined , requiring the development of high - throughput , automatic techniques for virus monitoring . Meanwhile , to reduce the chance of infection , it is important to develop practical methods for large - scale disinfection treatment of COVID - 19 virus in different environmental settings .

Background : The outbreak of coronavirus disease 2019 ( COVID - 19 ) has placed unprecedented challenges on hospital environmental hygiene and medical staff protection . It is crucial to assess hospital environmental hygiene to understand the most important environmental issues for controlling the spread of COVID - 19 in hospitals . Objective : To detect the presence of COVID - 19 in the samples from the area at risk of contamination in the First Hospital of Jilin University . Methods : Viruses in the air were collected by natural sedimentation and air particle sampler methods . Predetermined environmental surfaces were sampled using swabs at seven o ' clock in the morning before disinfection . The real - time reverse - transcription PCR method was used to detect the existence of COVID - 19 pathogens . Results : Viruses could be detected on the surfaces of the nurse station in the isolation area with suspected patients and in the air of the isolation ward with an intensive care patient . Conclusion : Comprehensive monitoring of hospital environmental hygiene during pandemic outbreaks is conducive to the refinement of hospital infection control . It is of great significance to ensure the safety of medical treatment and the quality of hospital infection control through the monitoring of environmental hygiene .

Risk of fatality among symptomatic hospitalized patients

Objective The outbreak of novel coronavirus disease 2019 ( COVID - 19 ) imposed a substantial health burden in mainland China and remains a global epidemic threat . Our objectives are to assess the case fatality risk ( CFR ) among COVID - 19 patients detected in mainland China , stratified by clinical category and age group . Method We collected individual information on laboratory - confirmed COVID - 19 cases from publicly available official sources from December 29 , 2019 to February 23 , 2020 . We explored the risk factors associated with mortality . We used methods accounting for right - censoring and survival analyses to estimate the CFR among detected cases . Results Of 12 , 863 cases reported outside Hubei , we obtained individual records for 9 , 651 cases , including 62 deaths and 1 , 449 discharged cases . The deceased were significantly older than discharged cases ( median age : 77 vs 39 years , p < 0 . 001 ) . 58 % ( 36 / 62 ) were male . Older age ( OR 1 . 18 per year ; 95 % CI : 1 . 14 to 1 . 22 ) , being male ( OR 2 . 02 ; 95 % CI : 1 . 02 to 4 . 03 ) , and being treated in less developed economic regions ( e . g . , West and Northeast vs . East , OR 3 . 93 ; 95 % CI : 1 . 74 to 8 . 85 ) were mortality risk factors . The estimated CFR was 0 . 89 - 1 . 24 % among all cases . The fatality risk among critical patients was 2 - fold higher than that among severe and critical patients , and 24 - fold higher than that among moderate , severe and critical patients . Conclusions Our estimates of CFR based on laboratory - confirmed cases ascertained outside of Hubei suggest that COVID - 19 is not as severe as severe acute respiratory syndrome and Middle East respiratory syndrome , but more similar to the mortality risk of 2009 H1N1 influenza pandemic in hospitalized patients . The fatality risk of COVID - 19 is higher in males and increases with age . Our study improves the severity assessment of the ongoing epidemic and can inform the COVID - 19 outbreak response in China and beyond .

Given advanced age and comorbidities , many patients with severe symptomatic aortic stenosis ( AS ) are at increased risk for COVID - 19 complications and death . However , multiple studies have also shown higher mortality among patients with severe symptomatic AS with a delay in treatment ( 2 , 3 ) over several months to years rather than weeks .

The effects of ALI at the early stage on death risk are presented in Table 3 . Among 151 COVID - 19 patients with cholestasis , 13 . 9 % were died . The fatality rate was higher among COVID - 19 patients with cholestasis than those without cholestasis ( 13 . 9 % vs 6 . 4 % ; RR = 2 . 182 , 95 % Cl : 1 . 129 , 4 . 218 ; P < 0 . 05 ) . As shown in Table 3 , there was no significant association between hepatocellular injury and death risk among COVID - 19 patients .

Many infected patients do not have symptoms , therefore it is difficult to estimate the case fatality rate . In patients hospitalized for severe symptoms , the case fatality rate is around 15 % . [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ] .

The PIBA model accurately predicted a case fatality of 1 . 6 % for symptomatic patients in

Risk of fatality among high-risk patient groups

Though 48 % of the non - survivors had a co - morbid disease , in multivariate analyses , independent associations of in - hospital death were found to be present with older age , high Sequential Organ Failure Assessment ( SOFA ) score and elevated d - dimer levels ( 6 ) . Another study has also identified older patients as a high risk group for mortality ( 7 ) . In agreement with previously published studies , our analysis also identified Age to be the most important risk factor for mortality among COVID - 19 patients . However , the role of delayed hospitalisation following the development of symptoms as another significant risk factor for mortality among COVID - 19 patients ( after Age ) is being reported for the first time . The inadequacy of healthcare resources has already been reported to associate with increased mortality among COVID - 19 patients ( 8 ) .

High proportion of severe to critical cases and high fatality rate were observed in the elderly patients with COVID - 19 . Rapid progress of disease was noted in the dead patients with a median survival time of 5 days after admission . Patients ' conditions on admission such as dyspnea , lymphocytopenia , cardiovascular disease and COPD , and the occurrence of ARDS during hospitalization were predictive of fatal outcome . Close monitoring and timely treatment should be performed for the elderly patients at high risk .

The effects of ALI at the early stage on death risk are presented in Table 3 . Among 151 COVID - 19 patients with cholestasis , 13 . 9 % were died . The fatality rate was higher among COVID - 19 patients with cholestasis than those without cholestasis ( 13 . 9 % vs 6 . 4 % ; RR = 2 . 182 , 95 % Cl : 1 . 129 , 4 . 218 ; P < 0 . 05 ) . As shown in Table 3 , there was no significant association between hepatocellular injury and death risk among COVID - 19 patients .

Objective The outbreak of novel coronavirus disease 2019 ( COVID - 19 ) imposed a substantial health burden in mainland China and remains a global epidemic threat . Our objectives are to assess the case fatality risk ( CFR ) among COVID - 19 patients detected in mainland China , stratified by clinical category and age group . Method We collected individual information on laboratory - confirmed COVID - 19 cases from publicly available official sources from December 29 , 2019 to February 23 , 2020 . We explored the risk factors associated with mortality . We used methods accounting for right - censoring and survival analyses to estimate the CFR among detected cases . Results Of 12 , 863 cases reported outside Hubei , we obtained individual records for 9 , 651 cases , including 62 deaths and 1 , 449 discharged cases . The deceased were significantly older than discharged cases ( median age : 77 vs 39 years , p < 0 . 001 ) . 58 % ( 36 / 62 ) were male . Older age ( OR 1 . 18 per year ; 95 % CI : 1 . 14 to 1 . 22 ) , being male ( OR 2 . 02 ; 95 % CI : 1 . 02 to 4 . 03 ) , and being treated in less developed economic regions ( e . g . , West and Northeast vs . East , OR 3 . 93 ; 95 % CI : 1 . 74 to 8 . 85 ) were mortality risk factors . The estimated CFR was 0 . 89 - 1 . 24 % among all cases . The fatality risk among critical patients was 2 - fold higher than that among severe and critical patients , and 24 - fold higher than that among moderate , severe and critical patients . Conclusions Our estimates of CFR based on laboratory - confirmed cases ascertained outside of Hubei suggest that COVID - 19 is not as severe as severe acute respiratory syndrome and Middle East respiratory syndrome , but more similar to the mortality risk of 2009 H1N1 influenza pandemic in hospitalized patients . The fatality risk of COVID - 19 is higher in males and increases with age . Our study improves the severity assessment of the ongoing epidemic and can inform the COVID - 19 outbreak response in China and beyond .

The fatality rate among patients with illness that meets the current WHO definition for probable and suspected cases of SARS ranges from 3 to 10 percent , depending on the age group and possibly other , yet unconfirmed , factors . 10 Furthermore , the mortality rate is higher among those with underlying illnesses and among the very elderly .

Susceptibility of populations

In the classic SIR model , S represents the susceptible population , I represents the infected population , and R represents the recovered population . Susceptible population can be infected , who would be cured or died of the infection . The composition of susceptible , infected , recovered , deceased population is modelled based on a set of transition probabilities .

( a ) In this study , Malaysia ' s population is divided into the SEIR compartmental model which consists of four compartments : Susceptible ( S ) , Exposed ( E ) , Infected ( I ) and Recovered ( R ) . The total population of Malaysia is denoted as N and it is assumed that the population is homogeneous . It is assumed that initially the total population is susceptible , hence S0 = N .

It is defined to be the average number of secondary cases generated by a typical case . A decrease in the susceptible population overtime will cause a corresponding decrease in the values of the reproduction number . It directly follows by Equation 8 that R 0 ( 0 ) = R 0 , as initially the total human population is assumed to be susceptible . The plot of R 0 ( t ) is similar to the plot of the susceptible portion , featured in Figure 3 in the manuscript . This is reasonable since Equation 8 implies that R 0 ( t ) is proportional to S ( t ) . Since δ ≈ 0 , the total population N ( t ) varies little within a tight envelope around the initial susceptible population S ( 0 ) . This is easily observable upon inspection of the dynamical system given by Equation 1 in the manuscript , as it is clear that

Traditional epidemiological models , such as the SIR and SEIR models , explain the rapid increase in the number of infections by the presence of a large susceptible population exposed to infection , and the decline of infection by the depletion of the susceptible population ( 7 ) . Such a model structure is questionable for capturing the spread of COVID - 19 due to the massive size of regional and global susceptible populations ( easily running into tens or hundreds of millions of residents in a region ) .

The model variables and parameters for the investigation of the stability analysis of the equilibrium state for the new deterministic endemic model is given by ; Proportion of population from susceptible to exposed / latent class Proportion of removed population still being observed and being moved to susceptible class ( ) Incidence rate or force of infection in the population

Public health mitigation measures that could be effective for control

The simulation results under scenarios ( 1 ) - ( 3 ) indicate that the public health control measures could effectively mitigate the COVID - 19 outbreak on the ship in terms of the final size , see Table 1 .

Therefore , governments across the world should revisit their emergency plan for controlling infectious disease outbreaks in the local context . Timely public health measures should be taken to control the outbreak within the city or the province / state where the city is located . Meanwhile , the supply of and demand for facemasks and other medical resources should be considered when planning for public health measures , so as to maintain the availability and affordability of medical resources . Besides , timely and effective communication with the public is essential to mitigate panic buying and anxiety in the population 27 , 28 . Furthermore , during a medical resource crisis , health disparity could be widened between specific population groups . Individuals of lower socioeconomic status are more likely to find themselves in a dilemma between the need to work in high - risk locations and the lack of protective equipment . In addition , market forces can drive the price up , preventing them from purchasing an adequate amount of protective equipment .

We need knowledge , attitude and practice studies in terms of acceptance and adherence to public health measures and other health initiatives for COVID - 19 . Accessing and addressing the physical health and psychosocial well - being of health care workers involved in care giving for COVID - 19 from time - to - time . Risk assessment and communication to address the public health needs and measures will help the general public to address their issues of anxiety , fear , and stigma associated with the COVID - 19 . There is also a need to understand the effect of restrictive public health measures used for management of COVID - 19 ( such as quarantine , isolation , lockdowns , etc . ) on the psychosocial and physical wellbeing of individuals . Socioeconomic status of the communities is also an important determinant for the compliance of sustainable public health measures . Public health information system must address pertinent issues based on dynamics of COVID - 19 and effectiveness of the control measures .

Social distancing measures are essential components of the public health response to COVID - 19 . The purpose of these mitigation measures is to reduce transmission , thereby delaying the peak of the epidemic , reducing the total number of infected people , and spreading new cases over a longer period of time to relieve the pressure on the health care system and achieve the purpose of controlling the epidemic ( Fong et al . , 2020 ) . The corresponding measures taken in Wuhan and Hubei Province have already seen practical results .

The results , in terms of a reduction in the number of cases and the rate of growth in case numbers , provide guidance to public health authorities as to how to optimise containment and control measures . Key questions that health authorities require guidance on involve the magnitude of social distancing interventions required to arrest virus spread , and include the strength , compliance rate , and duration of control measures required to be effective .