Prevalence of respiratory viruses in children in Northeast Brazil: The scenario before the COVID-19 pandemic.

Objectives: To investigate the prevalence of nine respiratory viruses and their clinical characteristics in children aged up to 5 years old in the state of Sergipe, Northeast of Brazil in the pre-COVID-19 pandemic period. Methods: Children with suspected influenza virus infection were included in the study. Clinical samples were screened using real-time quantitative polymerase chain reaction for the diagnosis of adenovirus, parainfluenza (PIV)1, PIV2, PIV3, and human metapneumovirus. In addition, data were collected for influenza A viruses (H1N1 and H3N2), influenza B virus, and respiratory syncytial virus. Results: From January 2018 to December 2019, 1081 samples were selected. Of these, 64.1% (n = 693) were positive for at least one of the nine screened respiratory viruses. The most prevalent etiologic agent in the study period was respiratory syncytial virus, detected in 31.8% (344 of 1081) of cases, and the least prevalent was the influenza B virus, detected in 0.6% (six of 1081) of cases. Single infections were found in 85.5% (594 of 693) of the cases, whereas 14.4% (100 of 693) had coinfections. There was no correlation when comparing reported signs and symptoms with real-time quantitative polymerase chain reaction positivity and the type of virus detected. The study highlights the importance of monitoring the etiological agents responsible for respiratory infections in children before the COVID-19 pandemic.