National Notifiable Disease Reporting System Research Articles

Epidemiological characteristics and spatio-temporal distribution patterns of human norovirus outbreaks in China, 2012-2018

Background and aim: Human norovirus are the leading cause of acute viral gastroenteritis worldwide. In China, the occurrence of norovirus outbreaks in different regions shows significant heterogeneity, while few study has focused on the spatial epidemiological characteristics of norovirus outbreaks. Thus, the aim of this study is to clarify the epidemiological characteristics and spatial distribution patterns of norovirus outbreaks. Methods: In China, according to the National Notifiable Disease Reporting System (NNDRS), 964 human norovirus outbreaks involving 50,548 cases in 26 provinces reported from 2012 to 2018 were analyzed in this study. Results: The outbreaks showed typical seasonality, with more outbreaks in winter and fewer in summer, and the total number of infected cases increased over time. The most common setting of norovirus outbreaks was school especially middle schools and primary schools with major transmission route of life-contact. More outbreaks occurred in southeast coastal areas of China and showed significant spatial aggregation. The highly clustered areas of norovirus outbreaks have expanded towards northeast over time. Conclusions: By identifying the epidemiological characteristics and high-risk areas of norovirus outbreaks, this study provides important scientific support for the development of preventive and control measures of norovirus outbreaks, which is conducive to the administrative management of high risk settings and reduction of disease burden in susceptible areas. Keywords: norovirus outbreak; epidemiological characteristics; spatio-temporal heterogeneity; spatio-temporal aggregation

Epidemiological Characteristics of Human Rabies - Shandong Province, China, 2010-2020.

IntroductionRabies is a viral zoonotic disease that causes progressive and fatal inflammation in the brain. Rabies has caused more than 5,000 human deaths in Shandong Province since 1955. This study aimed to analyze the epidemiological characteristics of human rabies in Shandong Province from 2010 to 2020 and to provide a scientific basis for policy changes.MethodsThe data of reported human rabies cases from 2010 to 2020 were obtained from China’s National Notifiable Disease Reporting System, and data related to exposure and post-exposure prophylaxis (PEP) of the cases were acquired through case investigation.ResultsA total of 414 human rabies cases were reported in Shandong Province from 2010 to 2020. Out of the 414 total cases, 87.20% were primarily farmers; 83.10% were over 40 years old. 70.29% (265/377) belonged to category Ⅲ exposure; and 96.67% (377/390) were exposed to the virus through infected dogs. The vaccine inoculation rate of these cases after exposure was only 8.85%; 1.03% (4/390) had been vaccinated with rabies immunoglobulin, developing the disease 11 to 13 days after category Ⅲ exposure.ConclusionsDogs were still the primary animal hosts. Most rabies patients died due to no or inadequate post-exposure prophylaxis. Vaccine inoculation rates for dogs should reach the target of 70% as soon as possible. Health departments should improve the accessibility and quality of PEP; and improve the health literacy of the elderly in rural areas.

Transmission Pattern of Measles Virus Circulating in China During 1993-2021: Genotyping Evidence Supports That China Is Approaching Measles Elimination.

To provide useful insights into measles elimination progress in China, measles surveillance data were reviewed, and the transmission patterns of measles viruses circulating in China during 1993-2021 were analyzed. Measles incidence data from the National Notifiable Disease Reporting System of the China Center for Disease Control and Prevention were analyzed. A total of 17 570 strains were obtained from 30 of 31 provinces in mainland China during 1993-2021. The recommended genotyping window was amplified. Genotyping analysis was conducted for comparison with the reference strains. Phylogenetic analyses were performed to identify genetic relationships among different lineages within the genotypes. With high coverage of routine immunization and intensive supplementary immunization activities, measles incidence has shown a downward trend since 1993, despite 2 resurgences, reaching a historic low level in 2020-2021 (average 0.5 per million). During 1993-2021, 9 genotypes including domestic genotype H1; imported genotypes B3, D4, D8, D9, D11, G3, and H2; and vaccine-associated genotype A were identified. Among them, the genotype H1 strain circulated endemically in China for more than 25 years; the last strain was detected in Yunnan Province in September 2019. Multiple imported genotypes have been identified since 2009 showing different transmission patterns. Since April 2020, no imported strains have been detected, while vaccine-associated genotype A continues to be detected. The evidence of low incidence during 2020-2021 and virological surveillance data in this study confirm that China is currently approaching measles elimination.

Assessment of mumps-containing vaccine effectiveness by dose during 2006 to 2020 in Quzhou, China

ABSTRACT Mumps cases were reported frequently when a routine dose measles–mumps–rubella(MMR) achieved high coverage in Quzhou. The supplementary immunization activities (SIA) using measles mumps (MM) was conducted to control mumps outbreaks. The effectiveness of one and two doses of mumps-containing vaccine (MuCV) was assessed using surveillance data in this study. Mumps cases and immunization information were retrieved from the National Notifiable Disease Reporting System (NNDRS) and the Zhejiang Provincial Immunization Information System (ZJIIS), respectively. Mumps cases of children born from 2006 to 2010 were included. Vaccine effectiveness by dose was calculated using the screening method. A total of 956 mumps cases were identified, of whom 754 (78.9%) had received one dose of MuCV; 108 (11.3%) had received two doses; 94 (9.8%) were unvaccinated. The coverage of one-dose MuCV in the 2006–2010 birth cohorts ranged from 91.6% to 98.9%. Except the 2009 birth cohort in which the coverage of two doses of MuCV was 55.1%, the others were less than 10%. Vaccine effectiveness (VE) of one dose ranged from 47.4% to 86.0%, while VE of two doses ranged from 64.0% to 92.4%. The VE of one and two doses of MuCV waned over time, but the VE of two doses was consistently higher than that of one dose in the same period. The vaccine schedule with two-dose MMR should be implemented among children in Quzhou. The optimal age for the second dose needs to be further evaluated.

Time to initial diagnosis of imported malaria and its influencing factors in Jiangsu Province

To investigate the health-seeking behaviors of imported malaria cases after returning to China, and to investigate the factors affecting the time to initial diagnosis, so as to provide the scientific evidence for early identification of imported malaria cases and prevention of severe cases development and secondary transmission. The individual demographic features, and the disease onset and the time to initial diagnosis of imported malaria cases in Jiangsu Province in 2019 were captured from the National Notifiable Disease Report System and the Information Management System for Parasitic Disease Control in China. The characteristics of health-seeking behaviors and epidemiological features of imported malaria cases were descriptively analyzed, and the factors affecting the time to initial diagnosis of imported malaria cases after returning to China were identified using multivariate logistic regression analysis. A total of 244 imported malaria cases were reported in Jiangsu Province in 2019, and the time to initial diagnosis of the cases were 1-12 days, with mean time of (1.53 ± 1.65) days, with median time of one day. The highest number of malaria cases seeking healthcare services were found on the day of developing primary symptoms (76 cases, 31.1%), followed by on the second day (68 cases, 27.9%), on the third day (46 cases, 18.9%), and 54 cases (22.1%) received initial diagnosis 3 days following presence of primary symptoms, including 3 cases with initial diagnosis at more than one week. High proportions of imported malaria cases with a delay in the time to initial diagnosis were seen in migrant workers who returned to China in January (14 cases, 5.7%) and December (13 cases, 5.3%) and those aged between 41 and 50 years (32 cases, 13.1%). Multivariate logistic regression analysis showed relative short time to initial diagnosis among imported malaria cases returning to China on March [odds ratio (OR) = 0.16, P = 0.03, 95% confidence interval (CI): (0.03, 0.85)] and those with a history of overseas malaria parasite infections [OR = 0.36, P = 0.001, 95% CI: (0.19, 0.67)]. Timely health-seeking behaviors should be improved among imported malaria cases in Jiangsu Province, patients with a history of overseas malaria infections require faster health-seeking activities.

Epidemic status of imported malaria before and after malaria elimination in Jiaozuo City of Henan Province

To analyze and compare the epidemiological characteristics of imported malaria in Jiaozuo City before and after malaria elimination, so as to provide insights into the malaria surveillance during the post-elimination stage and prevention of re-establishment of imported malaria. Data pertaining to the epidemic situation and individual investigation of malaria in Jiaozuo City before (from 2010 to 2016) and after malaria elimination (from 2017 to November, 2020) were captured from the National Notifiable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention of Chinese Center for Disease Control and Prevention and were analyzed statistically. A total of 74 imported malaria cases were reported in Jiaozuo City from 2010 to 2021. Imported cases were predominantly Plasmodium falciparum malaria cases in Jiaozuo City before and after malaria elimination, and there was no significant difference in the proportion of malaria parasite species (χ2 = 0.234, P > 0.05). The imported malaria cases was predominantly reported in Wuzhi County, and was identified in overseas male farmers and businessmen at ages of 20 to 59 years, while the greatest number of imported malaria cases was reported in June and December before and after malaria elimination. The imported malaria cases predominantly acquired malaria parasite infections in sub-Saharan African countries; however, the proportion of imported malaria cases returning from Southeast Asian counties increased after malaria elimination than before malaria elimination (χ2 = 5.989, P < 0.05). The longest duration from onset to definitive diagnosis of malaria reduced from 27 days before malaria elimination to 18 days after malaria elimination, and the median duration reduced from 3 days to 2 days, while the proportion of definitive diagnosis of malaria increased from 60.47% before malaria elimination to 83.87% after malaria elimination (χ2 = 4.724, P < 0.05). In addition, the proportion of malaria cases definitively diagnosed and reported by medical institutions increased after malaria elimination than before malaria elimination (χ2 = 5.406, P < 0.05). The imported malaria patients were predominantly P. falciparum malaria cases in Jiaozuo City during 2010 to 2021, and the patient's medical care-seeking awareness and medical staff's diagnosis and treatment ability have improved after malaria elimination. It is necessary to strengthen and improve malaria surveillance and response system and prevent the re-establishment of overseas imported malaria.

Epidemiological characteristics of imported respiratory infectious diseases in China, 2014\u20122018

BackgroundWith the progress of globalization, international mobility increases, greatly facilitating cross-border transmission of respiratory infectious diseases (RIDs). This study aimed to analyze the epidemiological characteristics and factors influencing imported RIDs, with the goal of providing evidence to support adoption of high-tech, intelligent methods to early find imported RIDs and prevent their spread in China.MethodsWe obtained data of imported RIDs cases from 2014 to 2018 from the Inbound Sentinel Network of Customs and the National Notifiable Diseases Reporting System in China. We analyzed spatial, temporal, and population distribution characteristics of the imported RIDs. We developed an index to describe seasonality. Pearson correlation coefficients were used to examine associations between independent variables and imported cases. Data analyses and visualizations were conducted with R software.ResultsFrom a total of 1 409 265 253 inbound travelers, 31 732 (2.25/100 000) imported RIDs cases were reported. RIDs cases were imported from 142 countries and five continents. The incidence of imported RIDs was nearly 5 times higher in 2018 (2.81/100 000) than in 2014 (0.58/100 000). Among foreigners, incidence rates were higher among males (5.32/100 000), 0–14-year-olds (15.15/100 000), and cases originating in Oceania (11.10/100 000). The vast majority (90.3%) of imported RIDs were influenza, with seasonality consistent with annual seasonality of influenza. The spatial distribution of imported RIDs was different between Chinese citizens and foreigners. Increases in inbound travel volume and the number of influenza cases in source countries were associated with the number of imported RIDs.ConclusionsOur study documented importation of RIDs into China from 142 countries. Inbound travel poses a significant risks bringing important RIDs to China. It is urgent to strengthen surveillance at customs of inbound travelers and establish an intelligent surveillance and early warning system to prevent importation of RIDs to China for preventing further spread within China.Graphical

Analysis of lactate dehydrogenase gene polymorphisms and prediction of B cell epitopes in four human Plasmodium species

To analyze the polymorphism of Plasmodium lactate dehydrogenase (pLDH) gene and predict B-cell epitopes in pLDH peptides in four species of human malaria parasites. The blood samples and epidemiological characteristics were collected from malaria cases in Yunnan Province registered in the National Notifiable Disease Report System. The pLDH genes of four human Plasmodium species were amplified using nested PCR assay and sequenced. The polymorphisms of pLDH genes was analyzed using the software MEGA version 7.0.26 and DnaSP version 5.10, and the B-cell epitopes were predicted in pLDH peptides using the Immune Epitope Database (IEDB). The sequences of P. vivax LDH (PvLDH), P. falciparum LDH (PfLDH), P. ovale LDH (PoLDH) and P. malariae LDH (PmLDH) genes were obtained from 153, 29, 17 and 11 blood samples from patients with P. vivax, P. falciparum, P. ovale and P. malariae malaria, respectively, which included 15, 2, 4 and 2 haplotypes and had a nucleotide diversity (π) of 0.104. A high level of intra-species differentiation was seen in the PoLDH gene (π = 0.012), and the π values were all < 0.001 for PvLDH, PfLDH and PmLDH genes. Active regions of B-cell antigen were predicted in the pLDH peptide chain of four human malaria parasites, of 4 to 5 in each chain, and the activity score was approximately 0.430. Among these peptide chains, the "86-PGKSDKEWNRD-96" short-peptide was a B-cell epitope shared by all four species of human malaria parasites, and the "266-GQYGHS (T)-271" short-peptide was present in PvLDH and PoLDH peptide chains, while "212-EEVEGIFDR-220" was only found in the PvLDH peptide chain, and "208-LISDAE-213" was only seen in the PfLDH peptide chain. The PoLDH gene polymorphism may be derived from the weak negative purification selection, while PvLDH, PfLDH and PmLDH genes may maintain a relatively conservative state. There may be two B-cell epitopes "212-EEVEGIFDR-220" and "208-LISDAE-213" in the proximal region of the C terminal in the pLDH peptide chain, which is feasible to differentiate between P. vivax and P. falciparum infections.

What are the risk factors of hospital length of stay in the novel coronavirus pneumonia (COVID-19) patients? A survival analysis in southwest China.

The global epidemic of novel coronavirus pneumonia (COVID-19) has resulted in substantial healthcare resource consumption. Since patients' hospital length of stay (LoS) is at stake in the process, an investigation of COVID-19 patients' LoS and its risk factors becomes urgent for a better understanding of regional capabilities to cope with COVID-19 outbreaks. First, we obtained retrospective data of confirmed COVID-19 patients in Sichuan province via National Notifiable Diseases Reporting System (NNDRS) and field surveys, including their demographic, epidemiological, clinical characteristics and LoS. Then we estimated the relationship between LoS and the possibly determinant factors, including demographic characteristics of confirmed patients, individual treatment behavior, local medical resources and hospital grade. The Kaplan-Meier method and the Cox Proportional Hazards Model were applied for single factor and multi-factor survival analysis. From January 16, 2020 to March 4, 2020, 538 human cases of COVID-19 infection were laboratory-confirmed, and were hospitalized for treatment, including 271 (50%) patients aged ≥ 45, 285 (53%) males, and 450 patients (84%) with mild symptoms. The median LoS was 19 (interquartile range (IQR): 14-23, range: 3-41) days. Univariate analysis showed that age and clinical grade were strongly related to LoS (P<0.01). Adjusted multivariate analysis showed that the longer LoS was associated with those aged ≥ 45 (Hazard ratio (HR): 0.74, 95% confidence interval (CI): 0.60-0.91), admission to provincial hospital (HR: 0.73, 95% CI: 0.54-0.99), and severe illness (HR: 0.66, 95% CI: 0.48-0.90). By contrast, the shorter LoS was linked with residential areas with more than 5.5 healthcare workers per 1,000 population (HR: 1.32, 95% CI: 1.05-1.65). Neither gender factor nor time interval from illness onset to diagnosis showed significant impact on LoS. Understanding COVID-19 patients' hospital LoS and its risk factors is critical for governments' efficient allocation of resources in respective regions. In areas with older and more vulnerable population and in want of primary medical resources, early reserving and strengthening of the construction of multi-level medical institutions are strongly suggested to cope with COVID-19 outbreaks.

Epidemiological features and diagnosis of malaria cases in Nantong City from 2015 to 2020

To investigate the epidemiological characteristics and diagnosis of malaria cases in Nantong City from 2015 to 2020, so as to provide insights into the prevention of re-establishment of imported malaria and consolidation of malaria elimination achievements in the city. The epidemic data of malaria in Nantong City from 2015 to 2020 were captured from the National Notifiable Disease Report System, the Information Management System for Parasitic Disease Control and individual epidemiological survey reports of malaria cases. The malaria parasite species, source of infections, population distribution, temporal distribution, spatial distribution and diagnosis of imported malaria cases were descriptively and statistically analyzed. A total of 241 malaria cases were reported in Nantong City from 2015 to 2020, and all were overseas imported cases, including 191 cases with Plasmodium falciparum malaria (79.25%), 8 cases with P. vivax malaria (3.32%), 33 cases with P. ovale malaria (13.69%) and 9 cases with P. malaria malaria (3.73%). Overseas imported malaria cases acquired infections from 34 countries in Asia, Africa and Latin America, and 97.93% of the cases were infected in Africa, and 90.04% (217/241) were reported in Chongchuan District, Hai'an City and Haimen District. Imported malaria cases were aged from 20 to 68 years, and a median age of 45 (13) years, and 97.10% were male. The median duration between returning to China and malaria onset was 7 (9) days among all imported malaria cases, and the median duration from initial diagnosis to definitive diagnosis was 2 (2) days. There were 167 cases that were initially diagnosed as malaria, with a correct rate of 69.29%, and 53.53 (129/241) of malaria cases were diagnosed at city-level medical institutions and 41.49% (100/241) at county-level medical institutions. In addition, the proportion of malaria cases reported by city-level medical institutions increased from 39.62% in 2015 to 81.25% in 2020 (χ2 = 6.94, P < 0.01). The accuracy of initial malaria diagnosis requires to be improved in Nantong City. Malaria control knowledge should be specially given to migrant workers to shorten the duration of seeking medical care, and malaria training requires to be intensified among healthcare professionals to improve the diagnostic capability of imported malaria cases and the cure of severe P. falciparum malaria cases.

Epidemiological characteristics of imported Plasmodium ovale malaria in Jiangsu Province from 2012 to 2020

To analyze the epidemiological characteristics of imported cases with Plasmodium ovale infections in Jiangsu Province from 2012 to 2020, so as to provide insights into the development of the imported malaria control strategy in the province. All data pertaining to cases with definitive diagnosis of P. ovale malaria in Jiangsu Province from 2012 to 2020 were captured from the National Notifiable Disease Report System and the Information Management System for Parasitic Disease Control in China, including the date of going abroad and returning to China, time of malaria infections overseas, date of malaria onset, initial diagnosis and definitive diagnosis. All data pertaining to epidemic status were descriptively analyzed. A total of 347 cases of P. ovale malaria were reported in Jiangsu Province from 2012 to 2020, with the highest number seen in 2015 (71 cases). All cases were laboratory-confirmed overseas imported malaria cases, accounting for 14.32% of all reported malaria cases in Jiangsu Province during the period from 2012 to 2020. The 5 cities with the highest number of imported P. ovale malaria cases included Lianyungang City (53 cases, 15.27%), Nantong City (44 cases, 12.68%), Huai'an (44 cases, 12.68%), Taizhou City (44 cases, 12.68%) and Yangzhou City (36 cases, 10.37%). The highest number of imported P. ovale malaria cases was reported in October (39 cases, 11.24%), and the lowest number was seen in December (21 cases, 6.05%). P. ovale infections mainly occurred in were Equatorial Guinea (97 cases, 37.95%), Angola (60 cases, 17.29%) and Nigeria (40 cases, 11.53%). The median duration between returning to China and malaria onset was 64 (144) days, and 7.49% (26/347) of all cases developed malaria one year after returning to China. The initial diagnosis of P. ovale malaria was mainly made at county-level medical institutions (117 cases, 33.72%), and the definitive diagnosis was mainly made at city-level medical institutions (122 cases, 35.16%). The correct rate of initial diagnosis of P. ovale malaria increased from 0 in 2012 to 78.26% in 2020, appearing a tendency towards a rise year by year (χ2 = 50.90, P < 0.01). Imported P. ovale malaria cases were reported in Jiangsu Province each year from 2012 to 2020, and P. ovale infections predominantly occurred in Africa. Initial and definitive diagnoses of P. ovale malaria were mainly made at city- and county-level medical institutions. Training on the detection ability of malaria parasites is recommended among grassroots microscopists to improve the diagnostic ability of P. ovale malaria, and consolidate the achievements of malaria elimination in Jiangsu Province.

Epidemiological characteristics of imported malaria in Zhengzhou City from 2016 to 2020

To analyze the epidemiological characteristics of reported imported malaria cases in Zhengzhou City from 2016 to 2020, so as to provide insights into the management of imported malaria in the city. All data pertaining to cases with definitive diagnosis of malaria in Zhengzhou City from 2016 to 2020 were captured from the National Notifiable Disease Report System and the Information Management System for Parasitic Disease Control in China, including individual demographic data, and malaria onset, initial diagnosis and definitive diagnosis data. All data were descriptively analyzed. The duration from malaria onset to initial diagnosis, from initial diagnosis to definitive diagnosis and from onset to definitive diagnosis was compared among cases. In addition, the diagnoses of imported malaria cases in which definitive diagnosis was made were compared with the reexaminations by Zhengzhou Municipal Malaria Diagnosis Reference Laboratory. A total of 302 cases with definitive diagnosis of malaria were reported in Zhengzhou City from 2016 to 2020, and all were imported cases, with Plasmodium falciparum malaria as the predominant type (230 cases, 76.2%). There were 293 malaria cases imported from Africa (293 cases, 97.0%), which mainly included Nigeria (48 cases, 15.9%), Angola (40 cases, 13.2%), and the Democratic Republic of the Congo (29 cases, 9.6%). There was no obvious seasonality found in the date of malaria onset and time of reporting malaria. The ratio of male to female malaria cases was 49.3:1, and there were 103 cases (34.1%) with the current residency address in Zhengzhou City, 193 cases (63.9%) with the current residency address in other cities of Henan Province and 6 cases (2.0%) in other provinces of China. There were 271 cases (89.7%) seeking initial diagnosis in medical institutions, and the diagnostic accuracy of malaria was 56.6% (171/302) at initial diagnosis institutions. A total of 122 cases (40.4%) sought medical care on the day of malaria onset, and 252 cases (86.4%) within 3 days; however, only 22 cases (7.3%) were definitively diagnosed on the day of onset, and 162 cases (53.6%) diagnosed within 3 days. There were no significant differences between malaria cases seeking initial diagnosis at medical institutions and disease control and prevention institutions in terms of the duration from malaria onset to initial diagnosis (Z = -1.663, P > 0.05), from initial diagnosis to definitive diagnosis (Z = -0.413, P > 0.05) or from malaria onset to definitive diagnosis (Z = -0.838, P > 0.05). The median duration (interquartile range) from initial diagnosis to definitive diagnosis of malaria was 3.00 (2.00), 3.00 (6.00), 2.00 (4.00) d and 1.00 (1.00) d among cases seeking medical care at township-level and lower, county-, city- and province-level medical institutions, and the median duration from initial diagnosis to definitive diagnosis of malaria was significantly longer among cases seeking medical care at township-level and lower medical institutions than at city (Z = -3.286, P < 0.008 33) and province-level medical institutions (Z = -9.119, P < 0.008 33), while the median duration from initial diagnosis to definitive diagnosis [1.00 (3.00) d vs. 2.00 (4.00) d; Z = -4.099, P < 0.016] and from malaria onset to definitive diagnosis [3.00 (4.00) d vs. 4.00 (5.00) d; Z = -2.868, P < 0.016] among malaria cases with the current residency address in Zhengzhou City was both shorter than in other cities of Henan Province. The diagnostic accuracy was 89.1% (269/302) among malaria cases in which definitive diagnosis was made, and the accuracy of malaria reexaminations was 94.0% (284/302) in Zhengzhou Municipal Malaria Diagnosis Reference Laboratory. P. falciparum malaria was predominant among reported imported malaria cases in Zhengzhou City from 2016 to 2020, and these imported malaria cases were predominantly diagnosed at medical institutions; however, the diagnostic capability of malaria is poor in township-level and lower medical institutions. Strengthening the collaboration between medical institutions and disease control and prevention institutions and improving the diagnostic capability building at medical institutions are recommended to consolidate malaria elimination achivements.

Epidemiological characteristics of imported COVID-19 cases in Tianjin

Objective: To understand the epidemiological characteristics of imported COVID-19 cases in Tianjin, and provide references for risk assessment and control of imported COVID-19 cases. Methods: The information of imported COVID-19 cases were obtained from National Notifiable Disease Report System of China CDC. The data of imported COVID-19 cases reported from Tianjin airport and epidemiological surveys by CDCs at all levels from March 15, 2020 to August 31, 2021 were collected and analyzed by using software Excel 2010, SPSS 25.0 and R. Results: From March 15, 2020 to August 31, 2021, a total of 606 imported cases of COVID-19 were reported in Tianjin, in which 552 cases were finally included in the analysis. The male to female ratio of the cases was 1.8∶1, the age of the cases ranged from 3 to 77 years, and the cases were mainly reported in age group 20-39 years (59.8%). The areas where the imported case sojourned within 14 days included Europe (242 cases, 43.8%), Africa (139 cases, 25.2%), Americas (85 cases, 15.4%) and Asia (86 cases, 15.6%). The proportion of confirmed cases in autumn and winter was relatively high. During the study period, the proportion of infected persons found in custom entry quarantine decreased, and the proportion of persons with personal health declaration and under medical isolation observation increased. The interval between entry and diagnosis of infected persons tended to increase. Conclusion: The proportion of imported COVID-19 cases detected on the first day of entry at Tianjin airport decreased, and the interval to detect the infected persons trended to increase, to which close attention must be paid.

Epidemiological characteristics of three local epidemics of COVID-19 in Guangzhou

Objective: To understand the epidemiological characteristics of three local COVID-19 epidemics in Guangzhou and provide reference for optimizing strategies and measures of COVID-19 prevention and control. Methods: The data of local COVID-19 cases in Guangzhou reported as of June 18, 2021 were collected from National Notifiable Disease Report System of China. The software Excel 2019 and SPSS 22.0 were applied for data cleaning and statistical analysis. Results: A total of 726 COVID-19 cases were reported in the three local epidemics in Guangzhou. In the epidemic associated with the outbreak of COVID-19 in Hubei province, 366 cases were reported. Most cases were female (51.6%, 189/366), aged 18-65 years (81.4%, 298/366), jobless/unemployed (32.2%, 118/366) and retired persons (20.2%,74/366). The initial symptoms of most cases were fever (71.6%, 250/349) and cough (60.7%, 212/349). In the epidemic associated with the imported COVID-19 cases from Africa, 207 cases were reported. Most cases were aged 18-40 years (72.9%, 151/207), male (69.6%, 144/207), and engaged in commercial services (62.3%,129/207). The initial symptoms of most cases were no obvious discomfort (55.6%, 15/27) and cough (37.0%, 10/27). In the epidemic associated with Delta variant of SARS-CoV-2, 153 cases were reported, in which women accounted for 58.8% (90/153), most cases were over 41 years old (64.7%,99/153), and retired persons accounted for the highest proportion (32.0%,49/153). The initial symptoms of most cases were cough (32.9%, 48/146) and no obvious discomfort (28.1%, 41/146). The household secondary attack rates of the three local epidemics were 11.2%, 5.7% and 11.5%, respectively. The median (P25, P75) of incubation periods were 6.5 (4.0,10.8) d, 4.0 (2.5, 6.0) d and 4.0 (3.0,5.0) d. The serial intervals median (P25, P75) were 4.0 (3.0, 8.0) d, 4.0 (2.5, 6.0) d and 3.0 (2.0,5.0) d. There were significant differences in gender, age, occupation, initial symptoms, household secondary attack rate and incubation period among the three local COVID-19 epidemics (all P<0.05). In the proportion of the case finding way, passive detection in patient treatment were mainly 44.3%(162/366) in the epidemic associated with the outbreak of COVID-19 in Hubei province,but active community case screening [58.5% (121/207) and 27.5% (24/153)] and close contact management in imported case were mostly [33.3% (69/207) and 67.3% (103/153)] in the epidemic associated with the imported COVID-19 cases from Africa and with Delta variant of SARS-CoV-2, respectively. Conclusions: Due to the different sources of infection, strain types and prevention and control strategies, the epidemiological characteristics of the three local COVID-19 epidemics in Guangzhou differed in demographics, clinical symptoms, transmission routes and case finding, which suggested that it is necessary to improve the key population and common symptom monitoring in the routine prevention and control of COVID-19 to prevent the reemerge of the epidemic.

Epidemiological characteristics of local outbreak of COVID-19 caused by SARS-CoV-2 Delta variant in Liwan district, Guangzhou

Objective: To analyze the epidemiological characteristics of a local outbreak of COVID-19 caused by SARS-CoV-2 B.1.617.2(Delta) variant in Liwan district, Guangzhou, and provide evidence for the further prevention and control of the Delta variant of COVID-19. Methods: From May 21 to June 18, 2021, the incidence data of COVID-19 caused by Delta variant were obtained from National Notifiable Disease Report System of Chinese Disease Prevention and Control Information System and Liwan District Center for Disease Control and Prevention of Guangzhou.Frequency analysis (proportions), histograms, and percentage stacked area plots were used to describe the epidemiological characteristics of the outbreaks. The incubation period and time-varying reproduction numbers (Rt) estimations were used for the further analysis. Results: By June 18, 2021, a total of 127 COVID-19 cases caused by Delta variant was reported in Liwan district. The youngest case was aged 2 years and the oldest was aged 85 years. There were 18.9% (24/127) aged <18 years, 43.3% (55/127) aged 18-59 years, and 37.8% (48/127) aged ≥60 years, the male to female ratio of the cases was 1∶1.35 (54∶73). The cases were mainly retired people (32.3%, 41/127), the jobless or unemployed (18.1%, 23/127), and students (16.5%, 21/127). The infections mainly occurred in Baihedong (70.1%, 89/127) and Zhongnan street (23.6%, 30/127) communities in the southern area of Liwan district. The median incubation period of the Delta variant infection was 6 days (range: 1-15 days). The clinical classification were mainly common type (64.6%, 82/127). The basic reproduction number (R0) was 5.1, Rt which once increased to 7.3. The transmissions mainly occurred in confined spaces, such as home (26.8%), restaurant (29.1%), neighborhood (3.9%), and market (3.1%), the household clustering was predominant. Close contacts tracing (66.1%) and community screening (33.1%) were the main ways to find the infections. Conclusion: The COVID-19 outbreak caused by Delta variant in Liwan district of Guangzhou was highly contagious, with the obvious characteristics of household clustering and high proportions of cases in adults aged 18-59 years and elderly people aged ≥60 years.

A survey of a COVID-19 cluster of charter flight importation

ObjectivesAlthough a number of cases of importation with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been reported, there are still no data available concerning the characteristics in the coronavirus disease 2019 (COVID-19) cluster of charter flight importation. Here, we provide an analysis of COVID-19 cases and their close contacts who worked for the same company on a project in Karbala, Iraq, and returned back to Chengdu, China, by a charter flight. MethodsThe data of imported COVID-19 cases and their close contacts were obtained from National Notifiable Disease Report System of Chinese Center for Disease Control and Prevention and field epidemiological investigation reports by Centers for Disease Control and Prevention (CDCs) in Chengdu. The information of general characteristics and laboratory findings of this cluster were collected and summarized. ResultsOne hundred and six (66.67%) of 159 charter flight passengers tested positive for COVID-19 before entry. Through treatment, all 159 people tested negative and meet the requirements of taking flights bound for China before boarding. However, there has been still 36 (22.64%) of them tested positive after entry. The median time from entry to confirmation was 1.0 day (Interquartile Range (IQR): 0–4.3). The Cycle threshold value (Ct value) of 36 patients’ positive samples are all above 30 and most values are above 35. ConclusionsIn conclusion, there is still a risk that a number of COVID-19 cases can be imported through charter flight. However, the infectivity of confirmed patients of the charter flight was considered to be low.

Estimation of incidence of viral hepatitis B and analysis on case characteristics in China,2013-2020

Objective: To understand the epidemiological characteristics of hepatitis B in China, evaluate the performance of elimination hepatitis B in China and provide scientific evidence for the prevention and control of hepatitis B. Methods: An analysis was conducted by using the data of hepatitis B cases reported to the National Notifiable Disease Reporting System (NNDRS) from the areas with low, moderate and high hepatitis B prevalence in China from 2013 to 2020, and the information about the diagnoses of the hepatitis B cases were collected, the incidence of hepatitis B was estimated according to the reporting and diagnosis information and the characteristics of acute and chronic hepatitis B were compared. Results: A total of 27 013 hepatitis B cases were reported to NNDRS, including 4 070 acute cases, 21 971 chronic cases and 972 unclassified cases. Among the reported acute hepatitis B cases, 69.9% (2 845/4 070) were confirmed. Among the reported chronic hepatitis B cases, 89.0% (19 548/21 971) were confirmed, and 2.1% (452/21 971) were confirmed as acute cases. It was estimated that the incidence of acute hepatitis B was 4.6/100 000 and the incidence of chronic hepatitis B cases was 54.5/100 000. The case number of acute hepatitis B in age group 31-45 years was highest, accounting for 35.3% (1 164/3 297). The case number of acute hepatitis B in children under 15 years old was lowest, accounting for 0.4% (13/3 297). The case number of chronic hepatitis B in age group 46-60 years was highest, accounting for 34.4% (7 211/20 932). Conclusions: The incidence of acute hepatitis B was in decrease and the incidence of chronic of hepatitis B was in increase in China year by year. It is important to strengthen the standardized diagnosis and treatment of chronic hepatitis B to decrease the morbidity and mortality of hepatitis B. At the same time, it is necessary to standardize the management and reporting of hepatitis B cases reported to NNDRS to improve the accuracy of the reporting of hepatitis B.

Epidemiological characteristics of imported cases of coronavirus disease 2019 in Chengdu, Sichuan

Objective To understand the epidemiological characteristics of imported coronavirus disease 2019 (COVID-19) cases detected in Chengdu, Sichuan, and provide scientific basis for the prevention and control of COVID-19. Methods The data of imported COVID-19 cases in Chengdu were obtained from National Notifiable Disease Report System of China CDC, field epidemiological investigation reports by CDCs in Chengdu, and flight related information from Chengdu airport. Software Epidata Manager, WPS 2019 and R 4.0.3 were used for data management and statistical analysis. Descriptive statistics and χ2 test were used to analyze the characteristics of the imported cases and inbound flights. Results As of November 30, 2020, a total of 90 900 passengers from 36 countries and regions via 677 inbound flights (including 44 chartered airplane flights) had entered China at Chengdu Shuangliu International Airport. The passengers were mainly from Asia(63.98%, 58 154/90 900), but the attack rate in flights from Africa was relatively high ( χ2=133.137, P Conclusion The imported cases of COVID-19 detected in Chengdu were mainly from countries or regions in Africa and Asia. Majority of the cases were sub-clinical, so strengthening the port case screening and close contact screening are essential to the prevention and control of COVID-19 in Chengdu, even in China.

Analysis of epidemiological serosurvey of hepatitis B virus among people under 29 years of age in Jiangsu Province, China

ABSTRACT Background: The purpose of this paper was to analyze the prevalence of hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), and hepatitis B core anti-body (anti-HBc)in1-29 years old living in the most populous eastern province of China,22 years after introduction of hepatitis B vaccine (HepB) vaccination of infants and provide provincial baseline data for developping a better prevention and control plan for hepatitis B virus (HBV)in Jiangsu Province, China Methods: The incidence rates of HBV in Jiangsu province from 2004 to 2014 were obtained from the National Notifiable Disease Reporting System (NNDRS). A stratified cluster random sampling method was used to select 3,002 participants aged 1–29 years across 13 HBV monitoring points throughout the province, which had been classified as either urban or rural. HBV serological markers were measured by Abbott microparticle enzyme immunoassay (MEIA) kits (Abbott Laboratories, Chicago, Illinois). Results: The incidence of hepatitis B decreased by approximately 71.44% in Jiangsu province between 2004 and 2014. Serological assessments showed that the prevalence of the HBsAg, anti-HBc, and anti-HBsin the 1–29 age group were 1.20%, 5.33%,and 66.89%, respectively. There was a significantly lower prevalence of HepB who were vaccinated than in unvaccinated subjects (0.46% vs 14.93%, p < .0001). Among these the ages of 1–29, the coverage rate drops from 97.7% to 56.6% with age,andthe timely rate among people aged 1–14 years was 90.93%. Conclusions: Since the HepB was integrated into the immunization programme in Jiangsu province,the rate of hepatitis B reported and the prevalence of HBsAg decreased significantly, and the coverage of HepB and the vaccination rate within 24 hours after birth have played an important role in reducing HBV infection.

Spatiotemporal distribution of measles in China, 2001-2016

Objective: To understand the spatial-temporal distribution and spatial clusters of measles cases in China. Methods: Measles incidence data was collected from the National Notifiable Disease Reporting System of Chinese Center for Disease Control and Prevention. The global and local spatial autocorrelation analyses were conducted by using software ArcGIS 10.2 and spatial-temporal scan was conducted by using software SaTScan 9.6. Results: A total of 1 012 537 cases of measles were reported in China from 2001 to 2016 and the annual incidence showed a sharp downward trend. There was global spatial clustering of measles cases during 2001-2004, 2005-2008, and 2009-2012, and their Moran's I coefficients were 0.29, 0.26, and 0.31, respectively. The results of local spatial autocorrelation analysis showed that there were high- high clustering areas of measles at all time periods, especially in western China. Guangdong province was detected as a separate high-low scattered area from 2005 to 2008 and no low-low clustering area was detected. The spatial-temporal scan statistics showed that there was a wide clustering area covering western, central and northern China, and Shanxi province and Guangxi Zhuang Autonomous Region from 2001-2008. Conclusion: The incidence of measles in China has a certain clustering in both space and time during 2001-2016, the results provide evidence for the development of future strategy of measles prevention and control in China.