# Shifting trends in influenza and rising HBoV cases: a comparative analysis over 3-winter seasons

## TL;DR

This study shows that after the pandemic, human bocavirus cases in children increased while influenza cases decreased, with co-infections leading to more severe illness.

## Contribution

The study reveals a significant shift in pediatric respiratory virus prevalence post-pandemic, emphasizing the rising role of HBoV1 and the impact of co-infections.

## Key findings

- HBoV1 prevalence increased from 9.5% to 20.8% post-pandemic.
- Influenza A/B infections declined significantly during the post-pandemic period.
- Co-infections were strongly linked to severe illness in children.

## Abstract

Acute respiratory tract infections (ARTIs) are a major cause of morbidity and hospitalization in pediatric populations. The COVID-19 pandemic has led to significant shifts in the epidemiology of respiratory viruses, particularly influenza viruses and human bocavirus 1 (HBoV1). This study aims to investigate the impact of the pandemic on the prevalence of HBoV1 and its clinical implications in pediatric ARTIs.

A retrospective cohort study was conducted in a tertiary pediatric emergency department (ED) over three consecutive winter seasons: the pre-pandemic period (2017–2019) and the post-pandemic period (2022–2024). Nasopharyngeal swabs were analyzed using multiplex polymerase chain reaction (PCR) to identify respiratory viruses. Clinical and demographic characteristics, hospitalization rates, disease severity, and outcomes were systematically evaluated.

Among 541 children (median age: 14 months), respiratory viruses were identified in 53.9%. The prevalence of HBoV1 increased significantly in the post-pandemic period (9.5% vs. 20.8%)(p < 0.001), whereas influenza A/B infections declined (p < 0.001). Co-infections decreased (13.4% to 5.3%), though HBoV1 was strongly linked to co-infections (p = 0.001). Severe illness was significantly associated with co-infections (aOR: 7.3, 95% CI: 3.9–14.2, p < 0.001) and age ≤ 1 year (aOR: 2.6, 95% CI: 1.2–5.1, p = 0.008).

The post-pandemic period is characterized by an increased prevalence of HBoV1 and a decline in influenza A/B infections. While HBoV1 alone does not appear to contribute to severe disease, co-infections, particularly with RSV, significantly increase morbidity. These findings highlight the need for continued viral surveillance and tailored clinical management strategies to address shifting epidemiological patterns in pediatric ARTIs.

Not applicable.