Background Rotavirus is a principal etiological agent of severe acute gastroenteritis in young children, for which vaccination constitutes the cornerstone of prophylactic intervention. However, to our knowledge, few studies have comprehensively assessed the differential population impacts of alternative rotavirus vaccination strategies within China. This study was therefore conducted to quantify the effect of vaccination on the epidemiological dynamics of rotavirus-associated gastroenteritis in Shanghai. Methods An age-structured Susceptible-Infected-Recovered-Susceptible (SIRS-type) compartmental model incorporating the effects of vaccine interventions was developed. Epidemiological data on reported cases were sourced from the infectious disease surveillance system. Scenario-based simulations were employed to evaluate vaccine efficacy and the prospective outcomes of strategic adjustments to the vaccination program. Results The model demonstrated a high degree of fit with observed epidemiological data over the calibration period from July 2015 to April 2024 (R2 = 0.747, RMSE = 58.55 cases/month; LOO R2 = 0.423). The implementation of the RotaTeq vaccination program resulted in an estimated cumulative reduction of 20.0% (95% CI: 18.9–21.6%) in the whole population and 24.6% (95% CI: 23.0–26.5%) among children under 5 years, relative to a no-RotaTeq counterfactual. Simulations indicated that optimizing the vaccination schedule of the Lanzhou lamb rotavirus vaccine (LLR) and augmenting coverage rates are effective strategies for outbreak mitigation. The introduction of Lanzhou lamb reassortant rotavirus vaccine, live, oral, trivalent (LLR3) and oral hexavalent reassortant rotavirus vaccine (WH-HRV) would further reduce the disease burden across all age groups, potentially controlling the epidemic to a minimal endemic level post-2029. Conclusions The incidence of rotavirus-associated gastroenteritis in Shanghai exhibited a discernible downward trend between 2015 and 2024, a decline associated with substantial contribution from the introduction of the RotaTeq vaccine. The optimization of existing vaccination protocols, in conjunction with the deployment of novel vaccines, is anticipated to be crucial for achieving more comprehensive and sustained control of rotavirus transmission in Shanghai.

BackgroundDiarrhea disease is a common intestinal infectious disease, and its incidence is affected by meteorological conditions. A better understanding of its epidemiological patterns and influencing factors, together with the construction of reliable prediction models, is of great significance for precise public health prevention and control. ObjectiveTo clarify the epidemic characteristics of adult diarrhea disease in Shanghai, analyze the associations of meteorological factors and a web search index with adult diarrhea disease, and develop and compare forecasting models to support precise regional prevention and control.MethodsWeekly surveillance data of adult diarrhea disease cases from the Shanghai Comprehensive Surveillance Information System for Diarrhea Diseases, together with concurrent meteorological observation data and web search index (Baidu index) data from 2014 to 2019, were collected. A distributed lag non-linear model (DLNM) was adopted to analyze the associations of multiple meteorological factors and the web search index with the number of diarrhea disease cases. By integrating meteorological factors and web search index data, three types of forecasting models were developed, including autoregressive integrated moving average (ARIMA), Random Forest, and extreme gradient boosting (Xgboost), and their predictive performances were evaluated.ResultsAdult diarrhea disease in Shanghai exhibited seasonal variation, with an major incidence peak in summer and winter peaks in some years. The number of cases declined annually after 2015. Mean temperature was significantly associated with the risk of diarrhea disease, and both low and high temperature exposures were associated with increased risks. The highest risk was observed at 32.8°C (RR=2.04, 95%CI: 1.62, 2.55), while the strongest effect of low temperature was observed at 0.9 °C (RR=1.53, 95%CI: 1.25, 1.88). When relative humidity exceeded 69%, the risk of diarrhea disease increased with relative humidity, reaching a peak at 81% (RR=1.20, 95%CI: 1.07, 1.35). When weekly cumulative precipitation exceeded 16 mm, the risk also increased with increasing precipitation, reaching a maximum at 105 mm (RR=1.23, 95%CI: 1.07, 1.42). The web search index was positively associated with the risk of diarrhea disease. Model prediction indicated that both the Random Forest model and the Xgboost model adequately captured the overall trend in diarrhea disease cases, with R2 values generally exceeding 0.7. Notably, the Xgboost model demonstrated greater accuracy in capturing peak intensities.ConclusionMeteorological factors are associated with adult diarrhea disease in Shanghai. The web search index may serve as an auxiliary indicator for diarrhea forecasting. Machine learning models, with advantages in integrating multisource data, may provide effective predictive tools for the prevention and control of diarrhea disease.

Introduction:The rapid evolution and symptom overlap of Coronavirus disease 2019 (COVID-19) and influenza challenge the effectiveness of current surveillance and healthcare resource planning. However, comparative evidence regarding their surveillance sensitivity and healthcare burden remains limited, particularly within concurrent community populations that capture the full spectrum of disease severity. Methods:To address this gap, data were derived from a community-based syndromic surveillance cohort in Shanghai, followed weekly between May 2024 and August 2025. We analyzed symptom profiles and illness duration, assessed the sensitivity of Influenza-Like Illness (ILI) definitions, and evaluated healthcare-seeking behaviors across both acute (0-14 days) and post-acute (>14 days) phases. Results:From May 2024 to August 2025, 382 COVID-19 and 175 influenza cases were identified. Compared with influenza, COVID-19 cases presented distinctively with upper respiratory symptoms (sore throat: 72.88% vs. 58.29%, runny or stuffy nose: 46.58% vs. 33.71%, loss of taste or smell: 3.84% vs. 0.57%; all p < 0.05), rather than fever (61.64% vs. 74.86%, p = 0.003). Consequently, standard ILI definitions failed to detect a significantly larger proportion of COVID-19 cases compared to influenza (China CDC criteria: 35.89% vs. 50.86%, p = 0.001; WHO criteria: 27.12% vs. 44.00%, p < 0.001). While illness duration was shorter for COVID-19 (6.66 ± 4.35 days vs. 8.25 ± 4.34 days, p < 0.05), influenza imposed a heavier healthcare burden, characterized by a two-fold increase in outpatient visits during the acute phase (OR = 2.12, 95% CI: 1.52-2.95) and sustained demand in the first 90 days of the post-acute phase (HR = 1.29, 95% CI: 1.03-1.61). Conclusion:COVID-19's symptom profile limits ILI surveillance sensitivity, whereas influenza imposes a higher burden extending into the post-acute phase. These differences call for adapting surveillance strategies and healthcare resource allocation to these distinct pathogen profiles.

[Objective]To investigate the current awareness and optimization recommendations on pneumonia with unknown etiology(PUE)surveillance among Shanghai healthcare professionals,and to provide evidence for the improvement of the surveillance system.[Methods]In December 2024,healthcare professional participants from diverse medical and health institutions were randomly selected within each stratum using a stratified cluster sampling method in all 16 districts of Shanghai for questionnaire surveys on their knowledge and suggestions for optimization of the PUE surveillance system.Descriptive statistics analyses,multivariate logistic regressions,and content analyses were used for data analyses.[Results]A total of 385 survey subjects were involved in the study,including 119 professional staffs from disease prevention and control centers and 266 from medical institutions.Those who understood the case definition for PUE correctly accounted for 67.01%(258/385).Multivariate regression model analyses showed that female gender(aOR=2.22,95%CI:1.36-3.66),professionals from disease control institutions(aOR=2.02,95%CI:1.12-3.72),and those who self-assessed as being familiar with the monitoring system(aOR=2.18,95%CI:1.23-3.89)had better understanding of the definition.Overall,89.61%(345/385)of the survey subjects acknowledged the necessity of the surveillance system.Small number of cases meeting the case definition(54.46%,214/379),insufficient diagnostic awareness(39.84%,151/379),and lack of incentives for case reporting(29.29%,111/379)were major problems for the current surveillance system,with variations observed across different types of institutions.Suggested segments for optimizing the surveillance system included monitoring purpose,case definition,form of monitoring and reporting procedure,organization mechanism,and epidemiological investigation and response.[Conclusion]The necessity of PUE surveillance is commonly recognized among healthcare workers.However,the existing system falls short in terms of mastery of case definition and overall surveillance adaptability.There is an urgent need for optimization and improvement to enhance the capacity for preventing and controlling emerging and sudden respiratory infectious diseases.

Objectives The number of post-marketing studies assessing the vaccine effectiveness (VE) of the Lanzhou lamb rotavirus vaccine (LLR, licensed in 2000 exclusively in China) and the oral human attenuated pentavalent rotavirus vaccine (RotaTeq, licensed in China in 2018) in China is limited. Methods A test-negative case-control study based on prospective surveillance was conducted among diarrhea patients aged 5 years and younger at five hospitals in Shanghai, China. Cases and controls were defined based on the results of real-time fluorescent quantitative reverse transcription polymerase chain reaction (rRT-PCR) of fecal samples for rotavirus. Both matched and unmatched case-control study designs were employed using logistic regression models, with adjustments for age at onset age and the rotavirus epidemic season. Results In the LLR-specific analysis (247 cases, 2191 controls), the VE of partial LLR vaccination (2 doses) was 49.09 % (95 % CI: 1.69 % ∼ 73.64 %) in multivariate analyses. In the RotaTeq-specific analysis (42 cases and 523 controls), the VE of complete RotaTeq vaccination was 87.13 % (95 % CI: 45.87 % ∼ 96.94 %), 89.46 % (95 % CI: 55.03 % ∼ 97.53 %), and 85.69 % (95 % CI: 33.43 % ∼ 96.93 %) respectively in univariate, multivariate, and matched analyses, respectively. The vaccination coverage for any dose among 2893 patients with rotavirus-negative diarrhea born between 2011 and 2022 was 49.78 %. Following the licensure of RotaTeq in 2018, this coverage increased from 45.02 % to 61.77 %. Conclusions RotaTeq demonstrates a robust protective effectiveness, while LLR provides a certain level of protection against mild to moderate rotavirus diarrhea in children in Shanghai. For privately purchased (non-NIP) vaccines, we estimate that the coverage for rotavirus vaccines among children in Shanghai is high. Complete rotavirus vaccination is recommended for age-eligible children. Further post-marketing research on rotavirus vaccines is necessary to inform decision-making regarding the introduction of rotavirus vaccination in China.

As COVID-19 transitions from pandemic to endemic, our prevention and control policies have shifted from broad, strict community interventions to focusing on the prevention of cluster outbreaks. Currently, information on the characteristics of cluster outbreaks remains limited. This study describes the features of COVID-19 clusters in Shanghai. It aims to provide valuable insights for managing localized outbreaks. We conducted a retrospective analysis of clusters of confirmed COVID-19 cases. Epidemiological descriptions, the transmission characteristics of clusters, and individual risk factors for contagiousness were analyzed. A total of 381 cases of COVID-19 were confirmed and 67 clusters were identified. Most clusters (58.21%, 39/67) only had two cases, with a declining proportion held by clusters of more cases. Familial transmission was predominant, accounting for 79.10% (53/67) of clusters. Although other types of cluster outbreaks, such as those in workplaces (1.49%, 1/67), occur less frequently compared to household clusters, they tend to involve larger scales and more cases. Workplaces and similar venues are more likely to experience large-scale cluster outbreaks. Contagiousness was higher among cases with runny nose (risk ratio [RR]: 4.8, 95% CI: 1.40-16.44, p-value = 0.01) and those with diabetes (RR: 3.8, 95% CI: 1.01-14.60, p-value = 0.05). In conclusion, household cluster outbreaks, in particular, are both a key priority and a foundational issue. Establishing an indicator system based on the transmissibility of cases holds significant practical value for infectious disease prevention and control. By enhancing household hygiene and developing a case classification and management system based on transmissibility, it is possible to better prevent and control regional COVID-19 outbreaks.

Introduction: This study investigated temporal changes in rotavirus group A (RVA) prevalence, epidemiological characteristics, and genotype distribution patterns among diarrhea outpatients in Shanghai Municipality, China. Methods: We conducted prospective active surveillance of diarrheal disease in pediatric and adult outpatients in Shanghai. Stool specimens were analyzed for five viral and twelve bacterial pathogens. Real-time reverse transcription polymerase chain reaction (rRT-PCR) was employed for RVA detection, followed by genotyping of RVA-positive specimens through partial amplification of VP7 and VP4 genes. Results: The study analyzed 2,331 diarrhea cases in children aged 0-14 years and 8,418 cases in individuals aged >= 15 years between January 2017 and December 2023. Overall RVA positivity rates decreased significantly from 7.43% in 2017 to 1.19% in 2023 (P=0.024). The most pronounced decline occurred in children aged 2-5 years, where positivity rates fell from 13.08% to 1.72%. Adults aged >= 30 years also showed a substantial reduction. Among RVA-positive pediatric cases (<= 14 years), the proportion of cases aged 6-14 years increased from 2.33% to 18.18%. While G9P[8] remained the predominant strain, its prevalence decreased from 77.78% to 31.25%, concurrent with the emergence of G8P[8] strains. Conclusions: RVA prevalence has shown a marked decline since 2018-2019, accompanied by a shift in age distribution toward older children. The diminishing dominance of G9P[8] strains coincided with the emergence of G8P[8] strains. Continued epidemiological and genetic surveillance of rotavirus diarrhea, coupled with real-world effectiveness evaluations of domestic vaccines, remains crucial for optimizing rotavirus immunization strategies.

IntroductionTo characterise age-mixing patterns among index cases and contacts of COVID-19, and explore when patients are most infectious during the disease process.MethodsThis study examined all initial 90 885 confirmed index cases in Shanghai and their 450 770 close contacts. A generalised additive mixed model was used to analyse the associations of the number of close contacts with different demographic and clinical characteristics. The effect of different exposure time windows on the infection of close contacts was evaluated using a modified mixed-effects Poisson regression.ResultsAnalysis of contacts indicated that 82 467 (18.29%; 95% CI 18.17%, 18.42%) were second-generation cases. Our result indicated the q-index was 0.300 (95% CI 0.298, 0.302) for overall contact matrix, and that assortativity was greatest for students (q-index=0.377; 95% CI 0.357, 0.396) and weakest for people working age not in the labour force (q-index=0.246; 95% CI 0.240, 0.252). The number of contacts was 4.96 individuals per index case (95% CI 4.86, 5.06). Contacts had a higher risk if they were exposed from 1 day before to 3 days after the onset of symptoms in the index patient, with a maximum at day 0 (adjusted relative risk (aRR)=1.52; 95% CI 1.30, 1.76). Contacts exposed from 3 days before to 3 days after an asymptomatic index case had a positive reverse transcriptase-PCR (RT-PCR) result had a higher risk, with a maximum on day 0 (aRR=1.48; 95% CI 1.37, 1.59).ConclusionsThe greatest assortativity was for students and weakest for people working age not in the labour force. Contact in the household was a significant contributor to the infection of close contacts. Contact tracing should focus on individuals who had contact soon before or soon after the onset of symptoms (or positive RT-PCR test) in the index case.

Background: Little is known about the characteristics of those who transmit SARS-CoV-2 infection vs those who do not, but this information could inform disease control policies. This study described the features of clusters in the first wave of COVID-19 in Shanghai and compared contagiousness by clinical and health care risk factors. Methods: In this retrospective cohort study of cases in Shanghai in January and February 2020, cases with successive generations were considered to be “contagious.” Characteristics of contagious and non-contagious cases were compared in log-binomial models that also adjusted for age and sex. Results: Between January 21 and February 17, 2020, 333 cases of COVID-19 were reported in Shanghai across 28 known infection chains. Contagiousness was higher among cases with a sore throat (risk ratio [RR]: 3.41, 95% CI: 1.59, 7.35, P=0.0051), and those with heart disease (RR: 2.06, 95% CI: 0.72, 5.90). Delays in diagnosis were also associated with higher risk of contagiousness. Having ≥2 medical visits before diagnosis was associated with 4.46 times higher risk of contagiousness (95% CI: 2.03, 9.83, P=0.0002), and there was a non-significant increase in risk with increasing numbers of days between disease onset and isolation (for each day, RR: 1.08, 95% CI: 1.01, 1.16, P=0.1734). Conclusions: Individuals with mild COVID-19 symptoms in the upper respiratory tract may still be contagious, and such individuals should be prioritized for early diagnosis and isolation to limit further chains of transmission.

Background From March to June 2022, an Omicron BA.2 epidemic occurred in Shanghai. We aimed to better understand the transmission dynamics and identify age-specific transmission characteristics for the epidemic. Methods Data on COVID-19 cases were collected from the Shanghai Municipal Health Commission during the period from 20th February to 1st June. The effective reproductive number (R t ) and transmission distance between cases were calculated. An age-structured SEIR model with social contact patterns was developed to reconstruct the transmission dynamics and evaluate age-specific transmission characteristics. Least square method was used to calibrate the model. Basic reproduction number (R 0 ) was estimated with next generation matrix. Results R 0 of Omicron variant was 7.9 (95% CI: 7.4 to 8.4). With strict interventions, R t had dropped quickly from 3.6 (95% CI: 2.7 to 4.7) on 4th March to below 1 on 18th April. The mean transmission distance of the Omicron epidemic in Shanghai was 13.4 km (95% CI: 11.1 to 15.8 km), which was threefold longer compared with that of epidemic caused by the wild-type virus in Wuhan, China. The model estimated that there would have been a total 870,845 (95% CI: 815,400 to 926,289) cases for the epidemic from 20th February to 15th June, and 27.7% (95% CI: 24.4% to 30.9%) cases would have been unascertained. People aged 50–59 years had the highest transmission risk 0.216 (95% CI: 0.210 to 0.222), and the highest secondary attack rate (47.62%, 95% CI: 38.71% to 56.53%). Conclusions The Omicron variant spread more quickly and widely than other variants and resulted in about one third cases unascertained for the recent outbreak in Shanghai. Prioritizing isolation and screening of people aged 40–59 might suppress the epidemic more effectively. Routine surveillance among people aged 40–59 years could also provide insight into the stage of the epidemic and the timely detection of new variants. Trial registration We did not involve clinical trial.

ObjectiveTo investigate an outbreak of norovirus diarrhea in a welfare home for the elderly in Shanghai， and to analyze the epidemiology and virus genotype characteristics of the epidemic， thus providing a scientific basis for the prevention and control of norovirus epidemic.MethodsCase definition was clarified. After case definition， a standardized questionnaire was used to carry out case investigation to make comprehensive analysis in combination with field epidemiological investigation and laboratory tests results.ResultsThe epidemic lasted for 14 days， and 23 cases were reported with an incidence rate of 12.37% （23/186）， including 3 males and 20 females. There were more cases on the 1st， 4th and 6th floor of the main building in the welfare home， accounting for 52.17% （12/23） of total cases. 19 cases were reported in the main building， with an incidence rate of 11.59% （19/164）； 4 cases were reported in the auxiliary building， with an incidence rate of 18.18% （4/22）. There was no significant difference in the morbidity between the main building and the auxiliary building （χ2=0.779，P>0.05）. The main clinical manifestations were vomiting and diarrhea. There was a significant difference in the incidence of vomiting symptoms among the elderly， nursing staff and other staff in the welfare home （χ2=10.216， P<0.05）. But there was no significant difference in the incidence of diarrhea among the elderly， nursing staff and other staff （χ2=1.218， P>0.05）. Fecal samples were collected from 23 cases， 1 case family member， 68 risk personnel and 14 environmental surface swab samples. Norovirus GⅡ was detected in stool samples of 19 cases， 1 family member and 36 risk personnel.ConclusionOutbreak of norovirus infection is reported in a welfare home in Shanghai. The close contact between the elderly and health workers might lead to the outbreak.

ObjectiveTo conduct on-site epidemiological investigation， emergency response， tracing of infection source and analysis of a confirmed COVID-19 case of a foreign airline cargo service staff member in Shanghai’s international airport， aiming to provide reference for prevention of imported COVID-19 cases under regular prevention and control of COVID-19.MethodsA retrospective field epidemiological investigation was conducted to collect information of basic characteristics， illness onset， diagnosis， treatment， clinical manifestations， exposure history and risk factors within 14 days before onset， close contacts， close contacts of close contacts， and key places related to activity trajectories. Respiratory tract specimens of cases and contacts were collected for detection of SARS-CoV-2 by real time RT-PCR （rRT-PCR）. Emergency response， including infection source analysis and contact management， was conducted.ResultsThe case developed pharyngeal itch on July 28， 2021， and fever on the 30th， and went to the hospital for treatment twice on the 31st. Because his specimen was positive for SARS-CoV-2 by rRT-PCR on August 1， he was isolated and treated on August 2 and diagnosed as a confirmed case of COVID-19. The case was a foreign airline cargo service member at an international airport. The two regular nucleic acid screenings of him as a high-risk occupation on July 21 and 28 were negative. He did not leave Shanghai within 14 days before the onset of illness. During July 22nd and 23rd， he was repeatedly exposed during work to the high-risk environment that may have been contaminated by SARS-CoV-2 and had contact with the crew of foreign airlines， and the personal protection was not standardized. None of the 67 close contacts and 567 close contacts of close contacts in Shanghai showed symptoms during the 14-day medical quarantine， and the specimens of them were all negative for SARS-CoV-2 by rRT-PCR. The results of genome sequencing analysis showed that the genomic homology between the virus of the case and the one of recent domestic local epidemic and the recent imported cases was low， and the homology with the overseas Delta mutant strain was higher than that of the domestic Delta mutant strain.ConclusionThe situation of prevention of COVID-19 import is still serious. It is necessary to conduct regular nucleic acid screening for high-risk occupational groups， strengthen the diagnosis and reporting awareness of medical institutions， effectively implement the prevention and control measures for people， objects， and environment at international airports， and further enhance the public's awareness of personal protection.

Background The duration of antibodies against SARS-CoV-2 in Covid-19 patients remains uncertain. Longitudinal serological studies are needed to prevent disease and transmission of the virus. Methods In 2020, 414 blood samples were tested, obtained from 157 confirmed Covid-19 patients, in a prospective cohort study in Shanghai. Results The seropositive rate of IgM peaked at 40.5% (17/42) within 1 month after illness onset and then declined. The seropositive rate of IgG was 90.6% (58/64) after 2 months, remained above 85% from 2 to 9 months and was 90.9% (40/44) after 9 months. Generalized estimating equations models suggested that IgM (P < 0.001) but not IgG significantly decreased over time. Age ≥ 40 years (adjusted odds ratio [aOR] 4.531; 95% confidence interval [CI] 1.879–10.932), and cigarette smoking (aOR 0.344; 95% CI 0.124–0.951) were associated with IgG, and age ≥ 40 years (aOR 2.820; 95% CI 1.579–5.036) was associated with IgM. After seroconversion, over 90% and 75.1% of subjects were estimated to remain IgG-positive 220 and 254 days, respectively. Of 1420 self-reported symptoms questionnaires, only 5% reported symptoms 9 months after onset. Conclusions In patients with a history of natural infection, anti-SARS-CoV-2 IgG is long-lived, being present for at least 9 months after illness onset. The long duration of natural immunity can mitigate and eliminate Covid-19 and the ongoing pandemic.

In order to meet the needs of prevention and control of intestinal infectious diseases， a comprehensive surveillance for diarrheal diseases has been innovated and explored in Shanghai since 2012. The surveillance has extensive distribution of sentinel hospitals， systematic sampling， multi-pathogen collection， and hospital information system （HIS） as the basis， which has achieved “One system for surveillance of multiple diseases and one sample for detection of multiple pathogens". Continual active surveillance for the whole population has been conducted， covering demography， clinical information， epidemiology， pathogen detection， and drug sensitivity test for diarrhea cases. The surveillance has obtained preliminary achievements as follows. First， diarrheal diseases and their periodic changes have been characterized， in which the most prevalent pathogen of diarrhea is determined to be norovirus in Shanghai. Second， some rare pathogens and serotypes have been identified that may provide clues to the sources of outbreaks. Third， it facilitates the information sharing between public health institutions and clinical institutions， and provides scientific evidence for clinical diagnosis and treatment. In the future， Shanghai diarrhea comprehensive surveillance will be improved for expanding range and depth of surveillance， artificial intelligence assisted diagnosis and treatment， early warning of outbreaks， prediction of epidemic trends， and application of new detection technologies.

目的 对上海市2020年1月20日—3月24日报告的所有新型冠状病毒肺炎(COVID-19)确诊病例进行疫情特征和防控情况分析,掌握本市疫情时空扩散特征、传播和变动的空间差异及与落实的防控措施之间的内在联系.方法 通过整理上海市卫生健康委员会官方网站疫情通告和COVID-19确诊病例流行病学调查资料,收集汇总病例的年龄、性别、确诊日期、感染来源等,运用描述性流行病学方法分析本市COVID-19确诊病例的疫情扩散特征和采取的各项防控措施.结果 上海市COVID-19确诊病例中,18～40岁青年人感染的比重较大,占39.03％(169/433);疫情共分为5个阶段,分别为第一次缓慢上升阶段、高速增长阶段、升速放缓阶段、维持"0"报告阶段和再次缓慢上升阶段;各阶段各类COVID-19确诊病例的报告和上海市采取的各项防控措施密不可分;本市疫情扩散比最高为0.502 2,各区在不同疫情发展阶段,疫情扩散比均表现为不同形态;总体而言,上海市COVID-19疫情防控措施是卓有成效的.结论 上海市疫情已进入新的防控阶段,应根据国外COVID-19疫情形势,采取针对性的防控措施,及时发现境外输入性病例.

目的 对上海市一起发生在公共场所的新型冠状病毒肺炎(COVID-19)聚集性疫情回顾性流行病学调查,分析疫情的感染来源、传播方式和传播链.方法 2020年1月-2月,对病例的基本情况、发病与诊疗、临床表现、发病前14天内暴露史和危险因素、密切接触者等信息现场流行病学调查,采集病例的呼吸道标本进行rRT-PCR新型冠状病毒核酸检测,分析病例间的流行病学关联及聚集性疫情的传播链.结果 该起聚集性疫情涉及4例确诊病例,其中3例曾在同一公共场所内活动.病例一2020年1月11日-16日至武汉出差,1月21日确诊;1月17日,病例一发病后至某客户服务中心,与病例二、病例三之间在未佩戴口罩和手套的情况下有多次接触;病例二1月28日发病,2月2日确诊;病例三1月21日发病,2月1日确诊;病例三的妻子病例四2月2日发病,2月4日确诊.与病例一的接触可能为病例二、病例三的感染来源,与病例三的共同生活可能为病例四的感染来源.结论 COVID-19可通过在公共场所的接触而传播导致聚集性疫情,需关注室内公共场所可能的传播风险、加强针对性的防控措施.

We report three clusters related with potential pre-symptomatic transmission of coronavirus disease (COVID-19) between January and February 2020 in Shanghai, China. Investigators interviewed suspected COVID-19 cases to collect epidemiological information, including demographic characteristics, illness onset, hospital visits, close contacts, activities' trajectories between 14 days before illness onset and isolation, and exposure histories. Respiratory specimens of suspected cases were collected and tested for SARS-CoV-2 by real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) assay. The interval between the onset of illness in the primary case and the last contact of the secondary case with the primary case in our report was 1 to 7 days. In Cluster 1 (five cases), illness onset in the five secondary cases was 2 to 5 days after the last contact with the primary case. In Cluster 2 (five cases) and Cluster 3 (four cases), the illness onset in secondary cases occurred prior to or on the same day as the onset in the primary cases. The study provides empirical evidence for transmission of COVID-19 during the incubation period and indicates that pre-symptomatic person-to-person transmission can occur following sufficient exposure to confirmed COVID-19 cases. The potential pre-symptomatic person-to-person transmission puts forward higher requirements for prevention and control measures.

We used contact tracing to document how COVID‐19 was transmitted across 5 generations involving 10 cases, starting with an individual who became ill on January 27. We calculated the incubation period of the cases as the interval between infection and development of symptoms. The median incubation period was 6.0 days (interquartile range, 3.5‐9.5 days). The last two generations were infected in public places, 3 and 4 days prior to the onset of illness in their infectors. Both had certain underlying conditions and comorbidity. Further identification of how individuals transmit prior to being symptomatic will have important consequences.