Recently,considerable efforts have been focused on intensifying the screening process for asymptomatic COVID-19 cases in the ChineseMainland,especially for up to 10 million citizens living in Wuhan City by nucleic ac...Recently,considerable efforts have been focused on intensifying the screening process for asymptomatic COVID-19 cases in the ChineseMainland,especially for up to 10 million citizens living in Wuhan City by nucleic acid testing.However,a high percentage of domestic asymptomatic cases did not develop into symptomatic ones,which is abnormal and has drawn considerable public attention.Here,we aimed to investigate the prevalence of COVID-19 infections in the Chinese Mainland from a statistical perspective,as it is of referential significance for other regions.By conservatively assuming a development time lag from pre-symptomatic(i.e.,referring to the infected cases that were screened before the COVID-19 symptom onset)to symptomatic as an incubation time of 5.2 days,our results indicated that 92.5%of those tested in Wuhan City,China,and 95.1%of those tested in the Chinese Mainland should have COVID-19 syndrome onset,which was extremely higher than their corresponding practical percentages of 0.8%and 3.3%,respectively.We propose that a certain false positive rate may exist if large-scale nucleic acid screening tests for asymptomatic cases are conducted in common communities with a low incidence rate.Despite adopting relatively high-sensitivity,high-specificity detection kits,we estimated a very low prevalence of COVID-19 infections,ranging from 106 to 104 in both Wuhan City and the Chinese Mainland.Thus,the prevalence rate of asymptomatic infections in China had been at a very low level.Furthermore,given the lower prevalence of the infection,close examination of the data for false positive results is necessary to minimize social and economic impacts.展开更多
The COVID-19 outbreak has already become a global pandemic and containing this rapid worldwide transmission is of great challenge.The impacts of temperature and humidity on the COVID-19 transmission rate are still und...The COVID-19 outbreak has already become a global pandemic and containing this rapid worldwide transmission is of great challenge.The impacts of temperature and humidity on the COVID-19 transmission rate are still under discussion.Here,we elucidated these relationships by utilizing two unique scenarios,repeated measurement and natural experiment,using the COVID-19 cases reported from January 23–February 21,2020,in China.The modeling results revealed that higher temperature was most strongly associated with decreased COVID-19 transmission at a lag time of 8 days.Relative humidity(RH)appeared to have only a slight effect.These findings were verified by assessing SARSCoV-2 infectivity under the relevant conditions of temperature(4C–37C)and RH(>40%).We concluded that temperature increase made an important,but not determined,contribution to restrain the COVID19 outbreak in China.It suggests that the emphasis of other effective controlling polices should be strictly implemented to restrain COVID19 transmission in cold seasons.展开更多
Summary What is already known about this topic?The coronavirus disease 2019(COVID-19)pandemic potentially affected prenatal care quality and maternal and fetal outcomes globally.What is added by this report?During COV...Summary What is already known about this topic?The coronavirus disease 2019(COVID-19)pandemic potentially affected prenatal care quality and maternal and fetal outcomes globally.What is added by this report?During COVID-19 pandemic period,the rates of caesarean sections(CS)and preterm birth for uninfected pregnant women increased slightly in areas that were relatively severely impacted by the pandemic in China.展开更多
文摘Recently,considerable efforts have been focused on intensifying the screening process for asymptomatic COVID-19 cases in the ChineseMainland,especially for up to 10 million citizens living in Wuhan City by nucleic acid testing.However,a high percentage of domestic asymptomatic cases did not develop into symptomatic ones,which is abnormal and has drawn considerable public attention.Here,we aimed to investigate the prevalence of COVID-19 infections in the Chinese Mainland from a statistical perspective,as it is of referential significance for other regions.By conservatively assuming a development time lag from pre-symptomatic(i.e.,referring to the infected cases that were screened before the COVID-19 symptom onset)to symptomatic as an incubation time of 5.2 days,our results indicated that 92.5%of those tested in Wuhan City,China,and 95.1%of those tested in the Chinese Mainland should have COVID-19 syndrome onset,which was extremely higher than their corresponding practical percentages of 0.8%and 3.3%,respectively.We propose that a certain false positive rate may exist if large-scale nucleic acid screening tests for asymptomatic cases are conducted in common communities with a low incidence rate.Despite adopting relatively high-sensitivity,high-specificity detection kits,we estimated a very low prevalence of COVID-19 infections,ranging from 106 to 104 in both Wuhan City and the Chinese Mainland.Thus,the prevalence rate of asymptomatic infections in China had been at a very low level.Furthermore,given the lower prevalence of the infection,close examination of the data for false positive results is necessary to minimize social and economic impacts.
基金We would like to express our gratitude for discussions with the researchers from the environmental exposure and human health working group of the China Cohort Consortium(http://chinacohort.bjmu.edu.cn/),as well as special thanks to Dr.Ping Zhong and Dr.Wentao Wang for their instructive guidance.This work was supported by the National Key Research and Development Program,P.R.China(Grant No.2020YFC0846300 and 2020YFC0846200)the National Natural Science Foundation of China(Grant No.41771527,41922057).
文摘The COVID-19 outbreak has already become a global pandemic and containing this rapid worldwide transmission is of great challenge.The impacts of temperature and humidity on the COVID-19 transmission rate are still under discussion.Here,we elucidated these relationships by utilizing two unique scenarios,repeated measurement and natural experiment,using the COVID-19 cases reported from January 23–February 21,2020,in China.The modeling results revealed that higher temperature was most strongly associated with decreased COVID-19 transmission at a lag time of 8 days.Relative humidity(RH)appeared to have only a slight effect.These findings were verified by assessing SARSCoV-2 infectivity under the relevant conditions of temperature(4C–37C)and RH(>40%).We concluded that temperature increase made an important,but not determined,contribution to restrain the COVID19 outbreak in China.It suggests that the emphasis of other effective controlling polices should be strictly implemented to restrain COVID19 transmission in cold seasons.
基金The Peking University ethics board(No.IRB00001052-20025)The National Key Research and Development Program,P.R.China(Grant No.2020YFC0846300)+1 种基金National Natural Science Foundation of China(Grant No.81673177,41771527)National Health Commission Capacity Building and Continuing Education Center(Grant No.:GWJJ2020100101).
文摘Summary What is already known about this topic?The coronavirus disease 2019(COVID-19)pandemic potentially affected prenatal care quality and maternal and fetal outcomes globally.What is added by this report?During COVID-19 pandemic period,the rates of caesarean sections(CS)and preterm birth for uninfected pregnant women increased slightly in areas that were relatively severely impacted by the pandemic in China.
