Investigating the Relationship between Climate and Hospital Admissions for Respiratory Diseases before and during the COVID-19 Pandemic in Brazil

This study aimed to analyze meteorological variables versus hospital admissions for respiratory diseases for the age groups of children under five and the elderly (over 65 years of age) in different climate regions of Brazil, for the years 2018 and 2020, i.e., before and after the outbreak of the COVID-19 pandemic. The aim of the study was, on one hand, to evaluate the influence of weather variables on respiratory disease in humans, and on the other hand, take into account two years with differing dynamics due to a worldwide pandemic that significantly changed people’s lifestyles. The human biometeorological index (Universal Thermal Climate Index, UTCI) was used as representative of the integral association of meteorological variables. UTCI data were obtained from the ERA5-HEAT reanalysis database, which provides hourly grid data with a spatial resolution of 0.25° × 0.25°. The Brazilian cities Manaus, Brasilia and Porto Alegre, which represent different climatic contexts in the country, were used in the analysis. The method compared temperature and climate reanalysis data to hospital admission data for respiratory diseases, obtained from the Brazilian Unified Health System database (DATASUS), according to the International Classification of Diseases, Tenth Edition (ICD-10). Correlation analysis was performed between variables (hospital admissions versus climate-related data) in order to identify associations between them, also accounting for different time-lag effects. We analyzed seasonal influences on the obtained correlations, correlation strength and direct or inverse relationships. Results showed that the pandemic interfered in the association between morbidity due to respiratory illnesses and climate-related variables.