While China experienced a peak and decline in coronavirus disease 2019 (COVID-19) cases at the start of 2020, regional outbreaks continuously emerged in subsequent months. Resurgences of COVID-19 have also been observed in many other countries. In Guangzhou, China, a small outbreak, involving less than 100 residents, emerged in March and April 2020, and comprehensive and near-real-time genomic surveillance of SARS-CoV-2 was conducted. When the numbers of confirmed cases among overseas travelers increased, public health measures were enhanced by shifting from self-quarantine to central quarantine and SARS-CoV-2 testing for all overseas travelers. In an analysis of 109 imported cases, we found diverse viral variants distributed in the global viral phylogeny, which were frequently shared within households but not among passengers on the same flight. In contrast to the viral diversity of imported cases, local transmission was predominately attributed to two specific variants imported from Africa, including local cases that reported no direct or indirect contact with imported cases. The introduction events of the virus were identified or deduced before the enhanced measures were taken. These results show the interventions were effective in containing the spread of SARS-CoV-2, and they rule out the possibility of cryptic transmission of viral variants from the first wave in January and February 2020. Our study provides evidence and emphasizes the importance of controls for overseas travelers in the context of the pandemic and exemplifies how viral genomic data can facilitate COVID-19 surveillance and inform public health mitigation strategies.

In the middle of March, the World Health Organization declared the outbreak of COVID-19 caused by SARS-CoV-2 infection a global pandemic. While China experienced a dramatic decline in daily growth rate of COVID-19, multiple importations of new cases from other countries and their related local infections caused a rapid rise. Between March 12 and April 15, we collected nasopharyngeal samples from 109 imported cases from 25 countries and 69 local cases in Guangzhou, China. In order to characterize the transmission patterns and genetic evolution of this virus among different populations, we sequenced the genome of SARS-CoV-2. The imported viral strains were assigned to lineages distributed in Europe (33.0%), America (17.4%), Africa (25.7%), or Southeast/West Asia (23.9%). Importantly, 10 imported cases from Africa formed two novel sub-lineages not identified in global tree previously. A detailed analysis showed that the imported viral strains from Philippines and Pakistan were closely related and within the same sub-lineage, whereas Ethiopia had varied lineages in the African phylogenetic tree. In spite of the diversity of imported SARS-CoV-2, 60 of 69 local infections could be traced back to two specific small lineages imported from Africa. A combined genetic and epidemiological analysis revealed a high-resolution transmission network of the imported SARS-CoV-2 in local communities, which might help inform the public health response and genomic surveillance in other cities and regions. Finally, we observed in-frame deletions on seven loci of SARS-CoV-2 genome, some of which were intra-host mutations, and they exhibited no enrichment on the S protein. Our findings provide new insight into the viral phylodynamics of SARS-CoV-2 and beta coronavirus.

手足口病主要由柯萨奇病毒A组16型(CVA16)与人肠道病毒71型(EV71)感染引起[1],也有少量由CVA6感染引起[2,3].本研究对2011年广州市手足口病标本检出的CVA6病毒开展分子流行病学研究. 1.材料与方法: (1)病例来源及诊断标准:病例来自广州市2011年5-10月哨点监测医院及各级疾病预防控制中心,共采集1 560名疑似手足口病患者标本,包括粪便1 450份、肛拭子74份、咽拭子35份、脑脊液l份,标本采集后及时-20℃冻存,冷藏运输至广州市疾病预防控制中心进行检测,标本处理方法见文献[3].诊断标准参见文献[4].同时收集临床资料.

Objective To identify the pathogens causing hand,foot and mouth disease(HFMD) in Guangzhou in 2011 and the distribution of their genotypes.Methods Specimens of suspected HFMD were collected.Partial VP1 genes were amplified by Real-Time RT-PCR or nested RT-PCR and then sequenced.Phylogenetic trees were constructed for correlation analysis.Results A total of 2 067 suspected HFMD cases were found.Enterovirus was identified in 1 139 cases,including 15 enteroviruses such as EV71,CoxA16,CoxA6,CoxA10,CoxA9,HEV96 and CoxB.CoxA16(39.2%),EV71(32.6%) and CoxA6(18.5%) were the major pathogens causing HFMD.There were 3 fatal cases and 6 severe cases caused by EV71.3 severe cases were caused by CoxA6.Phylogenetic analysis indicated that all pathogens identified in this study could be classified into HEV-A(97.2%),HEV-B(2.5%) and HEV-C(0.3%).No HEV-D was found.Conclusion EV71,CoxA16 and CoxA6 were the major pathogens causing HFMD.They all belong to HEV-A.There were sporadic cases caused by HEV-B(CoxA9,EC,CoxB) and HEV-C(CoxA24).

Objective To explore the epidemic trend of influenza A(H1N1) viruses outbreak through the investigation of antibodies of the influenza A(H1N1) viruses in the flu outbreak areas in Guangzhou.Methods Serum samples from 1 570 students living in the outbreak areas and 1 326 subjects living in the surveillance area were collected.The titers of antibodies to the influenza A(H1N1) viruses were detected by hemagglutination-inhition test.Results The infection rates and the incidence of influenza A(H1N1) infection were 32.17% and 22.23%,respectively,for the students living in the outbreak areas,compared to 22.62% and 15.38% in the surveillance populations.There were significant difference in the infection rates(P=0.000) and the incidence of influenza A(H1N1) infection(P=0.000) between the two groups.The rate of subclinical infection were respectively 9.94%(students in outbreak area) and 7.24%(surveillance populations)(P=0.012).There was no significant difference in the rate of subclinical infection between the two groups.The level of antibody of overt infections to influenza A(H1N1) was significantly higher than the recessive infections in the outbreak area students(t=4.701,P=0.000).There was no significant different in the level of antibody between clinical infections and subclinical infections in the surveillance populations(t=0.248,P=0.804).Conclusion The rate of subclinical infection to influenza A(H1N1) in the outbreak area students was higher than the surveillance populations.These results suggest that individuals with subclinical infection to influenza A(H1N1) may be the reservoir for this virus.It is important for the disease control to strengthen the viral surveillance and provide the preventive education in middle school during the period of H1N1 influenza pandemic.

BACKGROUND:To evaluate the risk of the recurrence and the efficiency of the vaccination, we followed-up antibody responses in patients with the 2009 pandemic H1N1 influenza and persons who received the pandemic H1N1 vaccine in Guangzhou China.METHODS:We collected serum samples from 129 patients and 86 vaccinated persons at day 0, 15, 30, 180 after the disease onset or the vaccination, respectively. Antibody titers in these serum samples were determined by haemagglutination inhibition (HI) assay using a local isolated virus strain A/Guangdong Liwan/SWL1538/2009(H1N1).RESULTS:HI antibody positive rate of the patients increased significantly from 0% to 60% at day 15 (χ(2) = 78, P<0.001) and 100% at day 30 (χ(2) = 23, P<0.001), but decreased significantly to 52% at day 180 (χ(2) = 38, P<0.001), while that of vaccinated subjects increased from 0% to 78% at day 15 (χ(2) = 110, P<0.001) and 81% at day 30 (χ(2) = 0.32, P = 0.57), but decreased significantly to 34% at day 180 (χ(2) = 39, P<0.001). Geometric mean titers (GMT) of HI antibodies in positive samples from the patients did not change significantly between day 15 and day 30 (T = 0.92, P = 0.36), but it decreased significantly from 80 at day 30 to 52 at day 180 (T = 4.5, P<0.001). GMT of vaccinated persons increased significantly from 100 at day 15 to 193 at day 30 (T = 4.5, P<0.001), but deceased significantly to 74 at day 180 (T = 5.1, P<0.001). Compared to the patients, the vaccinated subjects showed lower seroconversion rate (χ(2) = 11, P<0.001; χ(2) = 5.9, P = 0.015), but higher GMT (T = 6.0, P<0.001; T = 3.6, P = 0.001) at day 30 and day 180, respectively.CONCLUSION:Vaccination of 2009 influenza A (H1N1) was effective. However, about half or more recovered patients and vaccinated persons might have lost sufficient immunity against the recurrence of the viral infection after half a year. Vaccination or re-vaccination may be necessary for prevention of the recurrence.

This article has been retracted, please see Elsevier Policy on Article Withdrawal: http://www.elsevier.com/locate/withdrawalpolicy . This article has been retracted at the request of the editor as it duplicates significant parts of a paper that had already appeared in Orthopaedic Surgery (2009), Volume 1, No. 3, 207–211 DOI: 10.1111/j.1757-7861.2009.00033.x . One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and we apologize to readers of the journal that this was not detected during the submission process.

Objective To analyze the epidemiological characteristics of pandemic influenza A(H1N1) in Guangzhou.Methods The pharynx wash or swab specimens were collected weekly from influenza-like patients in four sentinel hospitals in Guangzhou from May 2009 to April 2010.Viral nucleic acid was extracted and examined for pandemic influenza A(H1N1) virus by real-time PCR;serum specimens were collected randomly in different age groups in 5 urban areas,and the antibody of pandemic influenza A(H1N1) were examined by hemagglutination-inhibition assay.The data were analyzed.Results 3 580 pharynx wash or swab specimens were collected.530(14.8%) were positive for pandemic influenza A(H1N1) virus detection.The positive rate reached the highest during October(36.5%) to December(42.3%).The highest positive rate was found in the age group 5-(18.5%) and 15-(24.2%),while the lowest(4.1%) was found in the age group above 60.1 527 serum specimens were collected.439(28.7%)of them were positive for antibody of pandemic influenza A(H1N1),the highest positive rate was found in the age group 5-(36.1%) and 15-(39.5%),while the lowest(8.6%)was found in the age group above 60.Conclusion The epidemic time of pandemic influenza A(H1N1) is short which is from October to December.The highest rate of infection occurred in school age persons,while the lowest rate was in the elders.The prevention of influenza should be focus on the school children.

In this two-years surveillance of 2009 pandemic influenza A (H1N1) (pH1N1) in Guangzhou, China, we reported here that the scale and duration of pH1N1 outbreaks, severe disease and fatality rates of pH1N1 patients were significantly lower or shorter in the second epidemic year (May 2010-April 2011) than those in the first epidemic year (May 2009-April 2010) (P<0.05), but similar to those of seasonal influenza (P>0.05). Similar to seasonal influenza, pre-existing chronic pulmonary diseases was a risk factor associated with fatal cases of pH1N1 influenza. Different from seasonal influenza, which occurred in spring/summer seasons annually, pH1N1 influenza mainly occurred in autumn/winter seasons in the first epidemic year, but prolonged to winter/spring season in the second epidemic year. The information suggests a tendency that the epidemics of pH1N1 influenza may probably further shift to spring/summer seasons and become a predominant subtype of seasonal influenza in coming years in Guangzhou, China.

据世界卫生组织(WHO)2010年2月初报告估计,全球共接种甲型H1N1流行性感冒(流感)疫苗1.75亿剂次.截至2010年3月9日24时,我国食品药品监督管理局累计完成批签发732批次13 786.1万人份流感疫苗.全国31个省(区、市)、新疆生产建设兵团累计签收疫苗10 485万人份,累计完成接种8217万人[1].在注射疫苗前,接种人群的背景调查至关重要[2],需尽可能排除疫苗带来的不良反应,特别是一些对疫苗接种有禁忌和顾虑的人群.在这类未接种人群中,甲型H1N1流感抗体阳性人群更是不需接种的对象.进行自然免疫血清抗体的摸底调查,排除自然免疫人群的接种,能避免重复免疫,节约社会资源;同时为开展疫苗接种前的抗体水平检测的必要性提供数据支持.

Background: A large number of 2009 pandemic influenza A (H1N1) infections were localized in school populations.Objectives: To describe the epidemiology, clinical features and risk factors associated with an outbreak that occurred at a vocational boarding school in Guangzhou, P. R. China.Study design: Data were collected prospectively and retrospectively through the use of on-site doctors and a post-outbreak survey and blood collection. The survey was used to confirm symptoms, and to investigate a series of flu-related factors such as dormitory conditions, health habits, vaccine history and population contact history. Blood samples were taken for serological analysis. Pandemic H1N1 infection was initially confirmed by a real-time RT-PCR assay. Following the identification of the outbreak by the Guangzhou CDC on September 4, cases were diagnosed symptomatically and retrospectively by serological analysis using the hemagglutination inhibition assay and a neutralization assay.Results: The infection rate was 32% (505/1570) and the attack rate was 22.2% (349/1570). The asymptomatic infection rate was 9.9% (156/1570). Sharing a classroom (OR = 2.17, 95% CI: 1.62-2.91) and dormitory space (OR = 2.32, 95% CI: 1.84-2.93) was associated with higher rates of infection. Opening windows for ventilation was the only control measure that significantly protected against infection.Conclusion: Social isolation and quarantine should be used to prevent the spread of infection. Ventilation and a control of air flow between classrooms and dorms should be implemented as possible. School closures may be effective if implemented early. (C) 2010 Published by Elsevier B.V.

目的分析广州市城区人群甲型H1N1流感病毒感染状况,了解甲型H1N1流感的流行病学特征。方法采用随机抽样的方法,在广州市5大城区采集不同年龄的、没有接种甲型H1N1流感疫苗的人群血清样本。采用血凝抑制试验检测血清中甲型H1N1流感病毒抗体。结果本次共调查1 326人,检出甲型H1N1流感病毒抗体阳性300例,阳性率为22.6%。不同年龄组人群的甲型H1N1流感病毒血清抗体阳性率差异有统计学意义(P<0.01),以5~14和15~24岁年龄组的阳性率最高,分别为32.9%(138/420)和31.6%(81/256)。300例甲型H1N1流感病毒血清抗体阳性者中,有96例(占32.0%)没有出现过流感样症状。结论学龄人群和年轻人群是广州市甲型H1N1流感病毒最大的感染群体。在感染人群里,有一定比例的人是没有出现流感样症状的。

为有效应对甲型H1N1流感疫情,评价疫苗的人群应用效果,本研究选取广州市自愿接种甲型H1N1流感疫苗的健康成年人,分别检测免前和免后第15天、第30天血清抗体滴度水平,对甲型H1N1流感裂解疫苗的人群免疫效果进行了观察。

ABSTRACT We present immunogenicity data on the routine vaccination of 103 health care personnel during the 2009 H1N1 national vaccination campaign. The seroprotection rate (percentage of samples with hemagglutination inhibition titers of ≥1:40) was 83.2% at 30 days postvaccination, lower than those obtained in previously published controlled trials. Low baseline antibody levels and an increase in seroprotection in a negative-control cohort suggest that the virus remains prevalent.

Objective To analysis the characteristics of influenza in Guangzhou in year 2007.Method The pharynx wash or swab specimens were collected from influenza-like patients in three sentinel hospitals,and were isolated by MDCK cells and examined by hemagglutination(HA)test and hemagglutination inhibition(HI)test;serum specimens were collected randomly in five different age groups:0,5,15,25,and 60,and were examined by hemagglutination inhibition(HI)test.Result 1068 specimens from influenza-like patients were isolated by MDCK cells.46 of those were identified as influenza virus,with the positive rate of 4.3%.Among those specimens,15(32.6%)were identified as H3N2,27(58.7%)were B(Yamagata),4(8.7%)were B(Victoria),and none of H1N1 was isolated.The highest positive rate(7.7%)was found in the group aged 60.The positive rate of influenza antibody in serum was low,with the highest of H3N2 antibody in serum collected in October(44%),the lowest of B(Yamagata)antibody in serum collected in March(6.7%).Conclusion The epidemic of influenza virus is seasonal and not so active.B(Yamagata)was the predominate subtype in 2007,it was epidemic in summer and the group aged 25.Influenza is a big threaten for the elders,and it is necessary to strengthen the prevention of influenza among the elders.