Detection of Respiratory Viruses Other Than SARS-CoV-2 in a Large Hospital Laboratory in Rome, Italy, During the Seasons 2016-2017 to 2022-2023.

Background and

Objective: Respiratory viruses are major contributors to morbidity and mortality worldwide, with their circulation influenced by seasonal patterns and pandemic-related interventions. This study analyzed detection trends of non-SARS-CoV-2 respiratory viruses in a large Italian hospital over a 7-year period, focusing on variations across COVID-19-related periods and patient age groups.

Methods: We retrospectively analyzed multiplex PCR-based laboratory results of 8836 nasopharyngeal samples collected between September 2016 and August 2023. Viral detection rates were stratified by season, COVID-19-related periods (pre-pandemic, pandemic, post-pandemic), and age groups.

Results: Of the 8836 nasopharyngeal samples analyzed, 2795 (31.6%) tested positive for at least one respiratory virus. Rhinovirus/enterovirus (RV/EV) was the most frequently detected virus (37.6%), followed by influenza A virus (IAV, 17.9%) and respiratory syncytial virus (RSV, 17.2%). The 2020-2021 season had the lowest positivity rate (p < 0.001), with marked declines in IAV and RSV detections, likely because of COVID-19 mitigation measures. Conversely, detections of RV/EV and human coronaviruses increased. Postpandemic data suggested a return to prepandemic patterns, though overall positivity rates remained altered. Age-stratified analysis revealed RSV predominance in infants (p < 0.001), emphasizing its clinical relevance in pediatric populations.

Conclusions: Our findings highlight the dynamic nature of respiratory virus epidemiology and the persistent impact of the COVID-19 pandemic on viral circulation. Continuous surveillance and adaptive public health strategies are essential for managing future outbreaks and mitigating the burden of respiratory viral infections.