Varicella emergency vaccination seemed instrumental in declining chickenpox incident in Guangzhou, Southern China

Effectiveness of varicella vaccination during an outbreak in a large one-dose-vaccinated population in Shanghai

Emergency vaccination (EV) is used as effective postexposure prophylaxis (PEP) to control varicella outbreaks within 3-5 days. However, the advantages of a second dose of varicella vaccine (VarV) in students who had received one dose before an outbreak and the potential benefits of EV at more than 5 days after exposure have not been fully evaluated. This study evaluated the vaccine effectiveness (VE) of EV in preventing disease development during a varicella outbreak in Shanghai, China, in 2020. Questionnaires were used to obtain student demographic information, clinical manifestations, varicella history, vaccination status, and willingness to receive EV. The VE of EV was calculated as [1-relative risk (RR)] ×100%. Among the 1455 students included in this study, 31 cases were identified, resulting in an overall attack rate of 2.13%. There were 6 cases in unvaccinated students and 25 cases in one-dose-vaccinated students. A total of 788 students received one EV dose. The attack rates were 6.38% (6/94), 4.26% (19/446), 2.82% (2/71), and 0.56% (4/717) among unvaccinated students, students who received 1 dose of VarV, and students who received EV with the 1^st and 2^nd dose of VarV, respectively. Compared to that in unvaccinated students, the VE of EV with the 2^nd dose of VarV was 88% (95% CI 49% to 97%). EV should be performed as soon as possible after exposure. Nevertheless, vaccination is still recommended at more than 5 days post exposure to control varicella outbreaks.

Association between the incidence of varicella and meteorological conditions in Jinan, Eastern China, 2012-2014

BACKGROUND

Varicella remains an important public health issue in China. In this study we explored the effect of weather conditions on the incidence of varicella in the temperate city of Jinan, Eastern China during 2012-2014 to inform public health prevention and control measures.

METHODS

Data on reported cases of varicella were obtained from National Notifiable Disease Report System. Meteorological data for the same time period were obtained from the Jinan Meteorological Bureau. A negative binomial regression model was used to assess the relationships between meteorological variables and the incidence of varicella. Given collinearity between average temperature and atmospheric pressure, separate models were constructed: one including average temperature without atmospheric pressure, the other including atmospheric pressure but without average temperature. Both models included relative humidity, wind velocity, rainfall, sunshine, and year as independent variables.

RESULTS

Annual incidence rates of varicella were 44.47, 53.69, and 46.81 per 100,000 for 2012, 2013, and 2014, respectively. Each increase of 100 Pa (hPa) in atmospheric pressure was estimated to be associated with an increase in weekly incidence of 3.35 % (95 % CI = 2.94-3.67 %), while a 1 °C rise in temperature was associated with a decrease of 3.44 % (95 % CI = -3.73-3.15 %) in the weekly incidence of varicella. Similarly, a 1 % rise in relative humidity corresponded to a decrease of 0.50 % or 1.00 %, a 1 h rise in sunshine corresponded to an increase of 1.10 % or 0.50 %, and a 1 mm rise in rainfall corresponded to an increase of 0.20 % or 0.30 %, in the weekly incidence of varicella cases, depending on the variable considered in the model.

CONCLUSION

Our findings show that weather factors have a significant influence on the incidence of varicella. Meteorological conditions should be considered as important predictors of varicella incidence in Jinan, Eastern China.

Correlation between clonorchiasis incidences and climatic factors in Guangzhou, China

BACKGROUND

Human infection with Clonorchis sinensis is still a big public health problem in Guangzhou. To investigate the correlation between clonorchiasis and climatic factors, we analyzed the clonorchiasis reported cases and simultaneous meteorological data during 2006-2012 in Guangzhou City, China.

FINDINGS

Annual incidence rate of clonorchiasis from 2006 to 2012 was 166.76, 191.55, 247.37, 213.82, 246.03, 274.71, and 239.63 (per 100 000), respectively. Each 1°C rise of temperature corresponded to an increase of 1.18% (95% CI 0.88% to 1.48%) in the monthly number of cases, and a one millimeter rise of rainfall corresponded to increase of 0.03% (95% CI 0.01% to 0.04%). Whereas each one percent rise of relative humidity corresponded to a decrease in the number of cases by 1.51% (95% CI -1.75% to -1.27%).

CONCLUSIONS

We reported incidence rates of clonorchiasis showed an increasing trend by years. Temperature and rainfall were positively associated with clonorchiasis incidence, while relative humidity was inversely associated with clonorchiasis incidence. Our study provided evidence that climatic factors affect the occurrence of clonorchiasis in Guangzhou city, China.