Spatial-temporal-demographic and virological changes of hand, foot and mouth disease incidence after vaccination in a vulnerable region of China.

BACKGROUND: The enterovirus 71 (EV-A71) vaccine has been used in Hefei for several years, and the epidemiological significance of vaccination in this area is unclear. We aims to explore the spatial-temporal-demographic and virological changes of hand, foot and mouth disease (HFMD) after vaccination in China. METHODS: The data for HFMD from 2012 to 2020 were downloaded with the help of HFMD reporting system of Hefei Center for Disease Control and Prevention and combined with the EV-A71 vaccination status in Hefei. The study defined the period between 2012 to 2016 as the pre-vaccination period and explored the effect of vaccination on the incidence of HFMD by comparing the changes of HFMD before and after vaccination in terms of spatial, temporal, demographic and virological aspects. RESULTS: During the study period, a higher incidence occurred in urban area and the random distribution changed to a slight cluster after vaccination. HFMD incidence had inconsistent seasonality over years, with one or two incidence peaks in varying years. The morbidity decreased from 215.22/105 in 2012-2016 to 179.81/105 in 2017-2020 (p < 0.001). Boys, 0-4 years old children and Scattered children were more susceptible to HFMD compared with the others, the proportions decreased after vaccination except in Scattered children. The main pathogenic enterovirus gradually changed from EV-A71 to Other Enteroviruses, especially coxsackieviruses A6 (CV-A6) after the implementation of EV-A71 vaccination. CONCLUSIONS: The EV-A71 vaccine was effective in reducing the incidence of HFMD and changing the spatial, temporal, demographic, and virological characteristic. These changes should be considered during the vaccination implementation to further reduce the disease burden of HFMD.

Effects of meteorological factors on the incidence of varicella in Lu'an, Eastern China, 2015-2020.

Varicella (chickenpox) is a serious public health problem in China, with the most reported cases among childhood vaccine-preventable infectious diseases, and its reported incidence has increased over 20-fold since 2005. Few previous studies have explored the association of multiple meteorological factors with varicella and considered the potential confounding effects of air pollutants. It is the first study to investigate and analyze the effects of multiple meteorological factors on varicella incidence, controlling for the confounding effects of various air pollutants. Daily meteorological and air pollution data and varicella cases were collected from January 1, 2015, to December 31, 2020, in Lu'an, Eastern China. A combination of the quasi-Poisson generalized additive model (GAM) and distributed lag nonlinear model (DLNM) was used to evaluate the meteorological factor-lag-varicella relationship, and the risk of varicella in extreme meteorological conditions. The maximum single-day lag effects of varicella were 1.288 (95%CI, 1.201-1.381, lag 16 day), 1.475 (95%CI, 1.152-1.889, lag 0 day), 1.307 (95%CI, 1.196-1.427, lag 16 day), 1.271 (95%CI, 0.981-1.647, lag 4 day), and 1.266 (95%CI, 1.162-1.378, lag 21 day), when mean temperature, diurnal temperature range (DTR), mean air pressure, wind speed, and sunshine hours were -5.8°C, 13.5°C, 1035.5 hPa, 6 m/s, and 0 h, respectively. At the maximum lag period, the overall effects of mean temperature and pressure on varicella showed W-shaped curves, peaked at 17.5°C (RR=2.085, 95%CI: 1.480-2.937) and 1035.5 hPa (RR=5.481, 95%CI: 1.813-16.577), while DTR showed an M-shaped curve and peaked at 4.4°C (RR=6.131, 95%CI: 1.120-33.570). Sunshine hours were positively correlated with varicella cases at the lag of 0-8 days and 0-9 days when sunshine duration exceeded 10 h. Furthermore, the lag effects of extreme meteorological factors on varicella cases were statistically significant, except for the extremely high wind speed. We found that mean temperature, mean air pressure, DTR, and sunshine hours had significant nonlinear effects on varicella incidence, which may be important predictors of varicella early warning.

Loss of protective immunity of two-dose mumps-containing vaccine over time: concerns with the new strategy of the mumps immunization program in China.

Background: Currently, children aged 6-9 years have the highest incidence rate of mumps in China. Although China has introduced a two-dose schedule of measles-mumps-rubella vaccine into routine immunization (at 8 months and 18 months), the incidence rate of mumps in high-risk populations might not decrease due to waning immunity. Here we report a mumps outbreak supporting this hypothesis.Methods: The descriptive epidemiological method was used to summarize the overall characteristics of the course of the outbreak. We conducted a retrospective cohort study to evaluate the vaccine effectiveness (VE) of mumps-containing vaccine (MuCV).Results: A total of 78 cases were identified during the outbreak and the estimated vaccination coverage was 84.7%. Of 454 vaccinated students, 335 (73.8%) had received one-dose MuCV, 93 (20.5%) two-dose, and 26 (5.7%) three-dose. The VEs for both the one-dose (-17.0%, 95%CI: -120.3-38.2%) and two-dose groups (-10.0%, 95%CI: -138.0-48.8%) were not performed well, whereas the VE for the three-dose group was 100%. However, we found that the overall VE was 74.2% (95% CI: 9.7-92.6%) for students vaccinated within 5 years. We also observed that there was a broadly linear increase in mumps infection risk in both one-dose and two-dose group when the time since last dose vaccination was more than 5 years.Conclusions: The overall VE for both one-dose and two-dose MuCV was discouraging, but it appeared to be moderately effective within 5 years after vaccination. Further surveillance and seroepidemiological data are needed to understand the impact of the new vaccination strategy on mumps in China.

Upgrading the school entry vaccination record check strategy to improve varicella vaccination coverage: results from a quasi-experiment study.

BACKGROUND: The school entry vaccination record check strategy (SECS) is an appropriate opportunity to recommend vaccines for students to improve vaccination coverage (VC). However, it is only utilized for providing necessary catch-up vaccination for students who are missing the Expanded Program on Immunization (EPI) vaccines in China. We aimed to address that gap and quantify the relationship between the SECS policy and the increase of coverage in varicella vaccine (VarV). METHODS: We employed a pretest and posttest quasi-experimental design to examine the effect of the upgraded SECS policy on the change of VarV coverage in newly enrolled students in Lu'an, 2019-2020. RESULTS: Eight hundred participants were randomly divided into the control group (C group, 31.8%), the telephone-based intervention group (T group, 31.2%), and the written notification intervention group (W group, 37.0%). Totally, 84 students received VarV during the study period, with a VC of 10.5%. The possibility of vaccination in the T group (RR = 4.9, 95% CI:2.2-10.9) and W group (RR = 5.2, 95% CI:2.4-11.5) was significantly higher than that in the C group (p< .001). CONCLUSIONS: Our study demonstrates that the upgraded SECS produce a positive effect on improving the VC of VarV. This nudge strategy may decrease varicella outbreaks in schools in China, especially in provinces where VarV is not introduced into EPI.