In recent years, outbreaks of varicella have continued to occur, and the coverage rate of varicella vaccine in Jiangsu Province, China, remains unclear. This study aims to analyse the levels of immune antibody against varicella and obtain a comprehensive understanding of the varicella attenuated live vaccine (VarV) coverage rate in children aged 1–9 years in Jiangsu Province. From June to October 2016, a cross-sectional survey was conducted to collect 3631 serum samples from healthy children aged 1–9 years in Jiangsu Province. The immunoglobulin G (IgG) antibody levels of varicella were detected by enzyme-linked immunosorbent assay (ELISA). The VarV coverage rate of healthy children was only 43.1% (95% CI: 41.1–44.7%). The seroprevalence after vaccination with a single dose of VarV was only 57.1%, and the overall seropositivity and geometric antibody titre (GMC) were 43.5% and 225.4 mU/ml, respectively. The seropositivity was significantly higher in girls than in boys (χ2 = 18.82, P < 0.001). The difference in seropositivity between the 5–9 age group and 1–4 age group was statistically significant (χ2 = 84.31, P < 0.001). The difference in seropositivity between different regions was statistically significant, with the highest seropositivity in the northern area, 53.7% (χ2 = 35.64, P < 0.001). The seropositivity in the group receiving one dose of VarV was significantly higher than that of the unvaccinated group (χ2 = 205.16, P < 0.001). Linear regression analysis suggested that the GMC of varicella antibodies wanes with the time since vaccination (F = 65.01, P = 0.002). The VarV coverage rate of healthy children in Jiangsu Province was low. Sero-conversion rates were also low after one dose of VarV, and the immune effectiveness of a single dose of VarV was limited. To control the spread of varicella, VarV should be included in the routine immunization program, and strengthened immunization measures for the varicella-susceptible population warrant additional consideration.

The mumps resurgence has frequently been reported around the world in recent years, especially in many counties mumps vaccines have been widely used. This study aimed to describe the spatial epidemiological characteristics of mumps in Jiangsu, and provide a scientific basis for the implementation and adjustment of strategies to prevent and control mumps. The epidemiological characteristics were described with ratio or proportion. Spatial autocorrelation, Tango's flexible spatial scan statistics, and Kulldorff's elliptic spatiotemporal scan statistics were applied to identify the spatial autocorrelation, detect hot and cold spots of mumps incidence, and aggregation areas. A total of 172 775 cases were reported from 2004 to 2020 in Jiangsu. The general trend of mumps incidence is declining with a bimodal seasonal distribution identified mainly in summer and winter, respectively. Children aged 5–10 years old are the main risk group. A migration trend of hot spots from southeast to northwest over time was found. Similar high-risk aggregations were detected in the northwestern parts through spatial-temporal analysis with the most likely cluster time frame around 2019. Local medical and health administrations should formulate and implement targeted health care policies and allocate health resources more appropriately corresponding to the epidemiological characteristics of mumps.

Background: The varicella vaccine is not included in the national childhood immunization schedules in China, although one-dose varicella vaccine has been suggested for susceptible children aged 1-12 years in Jiangsu Province. However, varicella epidemics and outbreaks are frequently reported. We investigated a varicella outbreak in an elementary school to explore the risk factors for varicella transmission and vaccine failure. Methods: A 1:2 matched case-control study was carried out. Participant data were collected with standardized questionnaires. For each case, we enrolled two controls: a subject with high exposure in the same classroom as the case and a subject with low exposure in a different classroom. Data regarding vaccination status and medical and exposure histories were analysed. Results: Fifty-one cases were reported during the outbreak; 26 cases (51%) were breakthrough varicella. Varicella vaccine immunization history (P<0.001, OR=0.19, 95% CI=0.08-0.45) and the presence of siblings (P=0.037, OR=0.45, 95% CI=0.21-0.95) were protective factors in preventing varicella infection. Contact with varicella patients increased the risk of varicella infection (P=0.028, OR=3.39, 95% CI=1.14-10.09). Breakthrough varicella cases tended to present a milder rash (P=0.049), fewer complications (P=0.02), fewer rash sites (P=0.02) and a shorter duration of active lesions (P=0.001). One pneumonia case and one encephalitis case were reported in breakthrough cases. Age <15 months at the time of vaccination increased the risk of breakthrough varicella (P=0.012). The adjusted vaccine effectiveness was 81%. Conclusions: One-dose varicella vaccine is effective at alleviating clinical manifestations. The moderate coverage provided by one dose cannot prevent varicella outbreaks, and vaccination after 15 months of age should be considered in the immunization schedule; a two-dose strategy is highly recommended.

Background: During the period of immunization with a single-dose measles-mumps-rubella (MMR) vaccine, which has been available since 2008in China, the incidence of mumps in children aged 2–5 years has been high. The aim of this study was to determine the immunity profile of mumps in children aged 2–5 years as part of the assessment of the MMR vaccination strategy. Methods: A cross-sectional survey of IgG antibodies against mumps virus in children aged 2–5 years was performed. Analysis by enzyme-linked immune sorbent assay(ELISA)was performed to measure IgG antibodies against mumps virus in the sera of 2-to5-year-old children who had been vaccinated with at least one dose of MMR vaccine. Results: Mumps outbreaks mainly occurred in kindergarten and primary schools and primarily involved children in kindergarten from 2015-2016 in Jiangsu Province. In total, 4,033 children were surveyed. The overall seroprevalence of mumps antibodies was 79.0% (95% CI:78.4–79.6), and the geometric mean concentration (GMC) was 323.6 mIU/ml (309.0–338.8). Both univariate and multivariate survival analysis of seroprevalence showed that several factors contributed to having significant seroprevalence among the 2-to-5-year-old group (P < .05). The seroprevalence of children with a single-dose MMR vaccine regimen (78.4%, 95% CI: 77.8–80.4) was significantly lower than that of children with a two-dose MMR vaccine regimen (96.5%, 95% CI: 88.6%-96.1%). The seroprevalence rate was negatively correlated with time since inoculation (P < .01). Conclusion: Children who received a single dose of MMR vaccine in kindergarten, particularly the 2-year-old group in the northern region of Jiangsu Province, China, are at high risk of mumps infection. Our study demonstrates thata single-dose MMR vaccine regimen has a limited effect on controlling mumps, which highlights the benefit of introducing a two-dose MMR vaccine schedule.

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.

Despite coverage of two doses of mumps-containing vaccines, mumps epidemics persist among children and young adults in China. This study aimed to analyze the epidemiological characteristics of mumps in Jiangsu Province, with a particular focus on breakthrough cases among high-incidence groups. Mumps cases reported in 2023 were systematically collected from the Infectious Disease Surveillance and Reporting System. A comprehensive descriptive epidemiological analysis was performed to elucidate the characteristics of the reported cases. A joinpoint regression (JPR) model was utilized to identify the temporal trends across various periods. Subsequently, immunization information for cases under 15 years of age was obtained through the Jiangsu Province Vaccination Integrated Service Management Information System to identify breakthrough cases and conduct exploratory analyses. A total of 4142 mumps cases were reported in Jiangsu Province in 2023, yielding an annual incidence rate of 4.86/100,000. A total of 81.75% of the cases were students and childcare children, and the gender ratio was 1.5:1 (male/female). The JPR model analysis of weekly reported cases identified five distinct trend segments (1st: 1–8, weekly percent change (WPC) = 26.67 *; 2nd: 9–28, WPC = 3.11 *; 3rd: 29–34, WPC = −5.31; 4th: 35–37, WPC = 15.48; 5th: 38–52, WPC = −4.06 *), and the gender subgroups demonstrated similar trends to the overall pattern. Notably, 89.14% (3692/4142) of the total cases were among individuals under 15 years, with 96.02% (3545/3692) having been vaccinated against mumps. The number of single-dose breakthrough cases (SdBCs) was approximately fourfold (2847/698) that of two-dose breakthrough cases (TdBCs). The main population composition of TdBCs was children aged 0–5 years old, and the classification was dominated by childcare children and scattered children. The median time interval between initial immunization and onset were shorter in TdBCs than in the SdBCs group, and the median time interval between the last immunization and onset was interestingly similarly shorter. However, these situations were interestingly reversed in 105 laboratory-confirmed breakthrough cases. Therefore, the current vaccination strategies have demonstrated tangible effectiveness in preventing and controlling mumps. However, the high incidence of breakthrough cases among high-risk pediatric populations indicates that mumps immunization strategies still deserve more attention and research for better herd protection.