Epidemiology of Influenza A among Children under Five Years in David-Chiriqui, Panama: A Five Year Surveillance Study

Abstract

Influenza is common among children and is associated with high hospitalization rates, particularly in those under five years of age. Global studies have shown that hospitalization rates due to laboratory-confirmed influenza infections have varied significantly before and after the COVID-19 pandemic. In this study, conducted from 2019 to 2023, we collected 2,696 nasopharyngeal swab samples from children under five years of age at the Jose Domingo de Obaldia Maternal and Children´s Hospital in David, Chiriqui, Panama. We performed real-time RT-PCR using specific primers for influenza A. Our findings revealed the presence of influenza A (H3N2) in 98 samples (19.7%) and influenza A (H1N1) in 17 samples (2.6%), with the A (H3N2) strain being the most frequently detected throughout the study period. In 2020, during the COVID-19 pandemic, no cases of influenza A (H1N1) were detected, and only two cases of influenza A (H3N2) were reported. Our study demonstrated a seasonal pattern of influenza A, with outbreak peaks occurring between May and September from 2019 to 2023. Previous research has shown that influenza A, particularly the (H3N2) strain, are undergoing unprecedented evolutionary genetic changes. According to data obtained from Panama´s Ministry of Health, pediatric deaths due to influenza were reported between 2019 and 2023. Based on these findings, we emphasize the urgent need to maintain epidemiological surveillance of influenza in David-Chiriqui, strengthen molecular studies, and conduct research on the genomic evolution of influenza viruses in Panama, which would provide essential information to support the development and design of new influenza vaccines.