Analyzing the relationship between air temperature and respiratory morbidity in children and the elderly in Porto Alegre, Brazil, before and during the COVID-19 pandemic.

The aim of the study was to analyze the relationship between air temperature data against hospital admissions due to respiratory diseases of children (under five years of age) and the elderly (over 65) in subtropical Porto Alegre, Brazil, comparing outcomes for 3 sequential years, 2018-2020, pre- and post-COVID 19 pandemic. Meteorological and hospital admission (HA) data for Porto Alegre, marked by a Koeppen-Geiger's Cfa climate type with well-defined seasons, were used in the analyses. HA was obtained for respiratory diseases (J00-99, according to the International Classification of Diseases, ICD-10) from the Brazilian DATASUS (Unified Health System database). We performed correlation analysis between variables (HA versus air temperature and heat stress) in order to identify existing relationships and lag effects (between meteorological condition and morbidity). Relative risk (RR) was also obtained for the two age groups during the three years. Results showed that the pandemic year disrupted observed patterns of association between analyzed variables, with either very low or non-existent correlations.