Association between varicella incidence and climate variability in Tucumán province, Argentina, 2005-2019

Abstract

INTRODUCTION: Varicella is a vaccine-preventable disease with marked seasonality. Few studies incorporate climatic variables to understand the epidemiological characteristics of this disease. The aim was to evaluate the relationship between varicella incidence and climatic variables in Tucumán (a province with temperate subtropical climate) during 2005-2019. METHODS: The relationship in pre- (2005-2014) and post-vaccination (2015-2019) periods was analyzed, identifying the associated climatic variables and the cut-off point where the risk of transmission increased. An observational ecological study was carried out with secondary data sources. R software was used. The information was split into three time series: 2005-2009, 2010-2014 and 2015-2019. For each period, a description of the time series was performed and generalized additive models (GAMs) were built using a negative binomial distribution. RESULTS: A seasonal behavior was observed, with peak incidence during spring in all periods. In the post-vaccination period, the peak occurred later (epidemiological week [EW] 46) than in the pre-vaccination periods (EW 43 and 42). Maximum temperature and relative humidity were associated during the first two periods, while minimum temperature, wind and thermal amplitude were associated in the third one. DISCUSSION: This study helped establish the relationship between climatic variables and varicella in Tucumán.