JMIR Publications

ABSTRACT

Background:

Varicella represents a widespread infectious disease with significant public health implications both in China and globally. It affects over 90% of unvaccinated individuals within populations.

Objective:

This study aims to assess the influence of meteorological variables on varicella incidence in Wuxi, a subtropical city in eastern China, spanning from 2010 to 2019. The findings offer insights for guiding public health interventions and strategies.

Methods:

We collected daily meteorological data and varicella case records from January 1, 2010, to December 31, 2019, in Wuxi City, Jiangsu Province, China. Generalized Cross Validation (GCV) was utilized to determine optimal lag days by evaluating models with varying lag periods. The lag days corresponding to the minimum GCV score were selected. The relationship between meteorological factors and varicella incidence was assessed through a combination of Poisson Generalized Additive Models (GAM) and segmented linear regression models. Subgroup analyses were conducted based on gender and age groups.

Results:

The study encompassed 64,086 varicella cases. Varicella incidence in Wuxi City exhibited a bimodal pattern annually, with peak occurrences observed from November to January of the subsequent year and lower peaks from May to June. We identified several meteorological factors influencing varicella risk. A decrease of 1 ℃ when temperatures were ≤ 20℃ corresponded to a 1.99% increase in varicella risk (95% CI: 1.57–2.42, p < 0.001). A decrease of 1 ℃ below 22.38℃ in the ground temperature increased varicella risk by 1.36% (95% CI: 0.96–1.75, p < 0.001). Each 1 mm increase in precipitation above 4.88 mm raised varicella incidence by 1.62% (95% CI: 0.93–2.30, p < 0.001). A 1% rise in relative humidity above 57.18% increased varicella risk by 2.05% (95% CI: 1.26–2.84, p < 0.001). An increase in air pressure of 1 hPa below 1011.277 hPa raised varicella risk by 1.75% (95% CI: 0.75–2.77, p < 0.001). As wind speed and evaporation increased, varicella risk decreased linearly with a 16-day lag. Varicella risk was higher with sunshine durations exceeding 1.825 hours with a 14-day lag, increasing by 1.30% for each additional hour (95% CI: 0.62–2.00, p = 0.00659). Subgroup analyses revealed higher varicella risks associated with temperature, average ground temperature, precipitation, relative humidity, and air pressure in children under 17 years old. Adults aged 18–64 years faced elevated risks with increased sunshine duration. Additionally, males exhibited higher varicella risks related to ground temperature and air pressure compared to females. However, no significant gender disparity was observed concerning temperature, precipitation, and sunshine duration-related varicella risks.

Conclusions:

Our preliminary findings shed light on the interplay between varicella outbreaks in Wuxi City and meteorological factors. These insights offer valuable support for crafting policies aimed at mitigating varicella risks through informed public health measures.