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BackgroundThe 2019 novel Coronavirus (COVID-19) emerged in Wuhan, China in December 2019 and has been spreading rapidly in China. Decisions about its pandemic threat and the appropriate level of public health response depend heavily on estimates of its basic reproduction number and assessments of interventions conducted in the early stages of the epidemic. MethodsWe conducted a mathematical modeling study using five independent methods to assess the basic reproduction number (R0) of COVID-19, using data on confirmed cases obtained from the China National Health Commission for the period 10th January - 8th February. We analyzed the data for the period before the closure of Wuhan city (10th January - 23rd January) and the post-closure period (23rd January - 8th February) and for the whole period, to assess both the epidemic risk of the virus and the effectiveness of the closure of Wuhan city on spread of COVID-19. FindingsBefore the closure of Wuhan city the basic reproduction number of COVID-19 was 4.38 (95% CI: 3.63 - 5.13), dropping to 3.41 (95% CI: 3.16 - 3.65) after the closure of Wuhan city. Over the entire epidemic period COVID-19 had a basic reproduction number of 3.39 (95% CI: 3.09 - 3.70), indicating it has a very high transmissibility. InterpretationCOVID-19 is a highly transmissible virus with a very high risk of epidemic outbreak once it emerges in metropolitan areas. The closure of Wuhan city was effective in reducing the severity of the epidemic, but even after closure of the city and the subsequent expansion of that closure to other parts of Hubei the virus remained extremely infectious. Emergency planners in other cities should consider this high infectiousness when considering responses to this virus. FundingNational Natural Science Foundation of China, China Medical Board, National Science and Technology Major Project of China
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Objective@#The number of confirmed and suspected cases of the COVID-19 in Hubei province is still increasing. However, the estimations of the basic reproduction number of COVID-19 varied greatly across studies. The objectives of this study are 1) to estimate the basic reproduction number (R0) of COVID-19 reflecting the infectiousness of the virus and 2) to assess the effectiveness of a range of controlling intervention.@*Method@#The reported number of daily confirmed cases from January 17 to February 8, 2020 in Hubei province were collected and used for model fit. Four methods, the exponential growth (EG), maximum likelihood estimation (ML), sequential Bayesian method (SB) and time dependent reproduction numbers (TD), were applied to estimate the R0.@*Result@#Among the four methods, the EG method fitted the data best. The estimated R0 was 3.49 (95% CI: 3.42-3.58) by using EG method. The R0 was estimated to be 2.95 (95%CI: 2.86-3.03) after taking control measures.@*Conclusion@#In the early stage of the epidemic, it is appropriate to estimate R0 using the EG method. Meanwhile, timely and effective control measures were warranted to further reduce the spread of COVID-19.
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Objectives@#Fitting and forecasting the trend of COVID-19 epidemics.@*Methods@#Based on SEIR dynamic model, considering the COVID-19 transmission mechanism, infection spectrum and prevention and control procedures, we developed SEIR+ CAQ dynamic model to fit the frequencies of laboratory confirmed cases obtained from the government official websites. The data from January 20, 2020 to February 7, 2020 were used to fit the model, while the left data between February 8-12 were used to evaluate the quality of forecasting.@*Results@#According to the cumulative number of confirmed cases between January 29 to February 7, the fitting bias of SEIR+ CAQ model for overall China (except for cases of Hubei province), Hubei province (except for cases of Wuhan city) and Wuhan city was less than 5%. For the data of subsequent 5 days between February 8 to 12, which were not included in the model fitting, the prediction biases were less than 10%. Regardless of the cases diagnosed by clinical examines, the numbers of daily emerging cases of China (Hubei province not included), Hubei Province (Wuhan city not included) and Wuhan city reached the peak in the early February. Under the current strength of prevention and control, the total number of laboratory- confirmed cases in overall China will reach 80 417 till February 29, 2020, respectively.@*Conclusions@#The proposed SEIR+ CAQ dynamic model fits and forecasts the trend of novel coronavirus pneumonia well and provides evidence for decision making.
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Objective The number of confirmed and suspected cases of the COVID-19 in Hubei province is still increasing. However, the estimations of the basic reproduction number of COVID-19 varied greatly across studies. The objectives of this study are 1) to estimate the basic reproduction number ( R 0 ) of COVID-19 reflecting the infectiousness of the virus and 2) to assess the effectiveness of a range of controlling intervention. Method The reported number of daily confirmed cases from January 17 to February 8, 2020 in Hubei province were collected and used for model fit. Four methods, the exponential growth (EG), maximum likelihood estimation (ML), sequential Bayesian method (SB) and time dependent reproduction numbers (TD), were applied to estimate the R 0 . Result Among the four methods, the EG method fitted the data best. The estimated R 0 was 3.49 (95% CI : 3.42-3.58) by using EG method. The R 0 was estimated to be 2.95 (95% CI : 2.86-3.03) after taking control measures. Conclusion In the early stage of the epidemic, it is appropriate to estimate R 0 using the EG method. Meanwhile, timely and effective control measures were warranted to further reduce the spread of COVID-19.
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Objective To investigate the value of standardized ultrasound screening in diagnosis of fetal congenital heart disease (CHD) during the first trimester. Methods This study retrospectively analyzed the clinical data of 8 383 fetuses who received ultrasound screening during the first trimester in the Dongguan Maternal and Child Health Hospital from September 2015 to December 2016. Standardized ultrasound was performed to observe fetal heart position, apical direction, apical four-chamber view, three vessels and trachea view and the thickness of nuchal translucency (NT). Fetuses with thickened NT or fetal CHD observed during the first and second trimester were followed up. Pregnancy outcomes and the growth of newborns within one year after birth were recorded and analyzed. Pathological results after the termination of pregnancy were compared with the results of routine karyotyping and chromosome microarray analysis (CMA). Results (1) A total of 27 cases of fetal CHD were identified during the first trimester giving a detection rate of 0.32% (27/8 383). These included ten (37.0%) of single atrium and/or single ventricle, seven (25.9%) of endocardial cushion defect (including two complicated by persistent arterial trunk), three (11.1%) of hypoplastic right heart syndrome, three (11.1%) of interventricular septal defect, two (7.4%) of hypoplastic left heart syndrome, one (3.7%) of mirror-image dextrocardia and one (3.7%) of right atrial enlargement and severe tricuspid regurgitation. Nineteen out of the 27 cases had NT thickening (NT≥3.0 mm) and 17 of them had a cystic hygroma (NT≥6.0 mm). Among the 27 cases, 22 were terminated in the first trimester which autopsy results were consistent with ultrasound and the other five were rescreened during the second trimester. Thirteen out of the 27 cases received chorionic villus sampling, and seven of them were found to have chromosomal abnormalities by karyotyping and CMA, among whom one was microdeletion of 22q11. (2) Twenty-one cases of CHD were detected in the second-trimester ultrasound screening, including five initially identified in the first trimester. These cases included four (19.0%) of complex cardiac malformations (with three or more malformations), four (19.0%) of interventricular septal defect, three (14.3%) of dextroaortic arch, left subclavian artery vagus and 'U' shaped vascular ring, three (14.3%) of hypoplastic right heart syndrome (including one complicated by coronary artery-right ventricular fistula and one by interventricular septal defect), two (9.5%) of transposition of the great arteries, two (9.5%) of tetralogy of Fallot, one (4.8%) of hypoplastic left heart syndrome, one (4.8%) of Taussig-Bing anomaly and one (4.8%) of coarctation of the aorta. Among the 16 cases first identified in the second trimester, eight had NT thickening, including one with cystic hygroma. Among the 21 cases, two were lost to follow-up after being transferred to another hospital; four with negative results in karyotype analysis and CMA were delivered vaginally at term (37-40 gestational weeks) with 1-min Apgar scores of ten points and postpartum ultrasound of the baby was consistent with the second-trimester ultrasound screening; 15 were terminated and the autopsy confirmed those findings in the second-trimester ultrasound screening. Eleven out of the 21 cases received amniocentesis and five of them were found to be abnormal according to karyotype analysis and CMA, including one of microdeletion of 22q11. Conclusions Standardized first-trimester ultrasound screening is important and of great clinical value in the diagnosis of fetal CHD. Increased NT thickness could be a key indicator of fetal CHD and chromosomal abnormalities in early pregnancy. CMA may facilitate detecting the abnormality of genetic material in fetuses with normal chromosome karyotype.
