Prevalence of common respiratory viruses of infants with respiratory tract infections in European countries in the past decade: a systematic review and meta-analysis comparing between the pre-COVID-19, pandemic, and post-COVID-19 periods

Abstract The purpose of this study is. to determine the leading cause of respiratory tract infections over the decade; this review examined the proportions of airway viruses in infants with respiratory tract infections in Europe before, during, and after the COVID-19 pandemic. The protocol for this systematic review was registered in the PROSPERO database (CRD42024497097). Literature searches in PubMed, Embase, Scopus, and Web of Science (WoS) identified 20,453 studies reporting respiratory viral testing in Europe over the past decade (2012/13–2022/23). Eligible studies were English-language full-text or grey articles with low risk of bias and complete data, and reports that explicitly provided the number of positive airway virus cases ( n , virus) and the total infant population ( N ). Risk of bias was assessed using the Hoy et al. scoring system. Pooled prevalence estimates (pooled proportion [95% CI]) were calculated for pre-, during-, and post-COVID-19 periods using proportional meta-analysis with the MetaProp package in R. Fifty studies before, ten studies during, and 18 studies after the COVID-19 pandemic were eligible for proportional meta-analyses of viral testing in infants. Before the pandemic, the predominant viruses in infants with respiratory infections were Respiratory Syncytial Virus (RSV) (0.48 [0.41–0.56]), Human rhinovirus (HRV) (0.24 [0.18–0.29]), and Influenza virus (IV) (0.08 [0.04–0.12]). Post-pandemic, the leading viruses were RSV (0.63 [0.51–0.75]), HRV (0.25 [0.11–0.40]), and IV (0.10 [0.00–0.20]) again. Conclusions : RSV and HRV remained the two most identified viruses in infants with respiratory infections, pre- and post-COVID-19 pandemic. Interestingly, both RSV and IV were suppressed during the pandemic. The trajectory dynamics of respiratory viruses were divergent, with resilient viruses (RSV, HRV, and IV) regaining dominance more rapidly than persistently suppressed viruses. What is Known: • The COVID-19 pandemic induced an infection precautions policy, which reduced the spread of respiratory infectious diseases. • Respiratory Syncytial Virus (RSV) was estimated as one of the most common causes of respiratory infections in infants. Still, there are no reports summarising the geographical distributions of the various viral agents of infant respiratory diseases. What is New: • This meta-analysis shows that the prevalence of RSV and HRV infections in infants remains high in Europe following the COVID-19 pandemic and the associated precautionary policy. Furthermore, RSV proportionally experienced a marked reduction during COVID-19 pandemic (lockdown periods). However, the immunological debt may have led to a re-emergence in RSV positivity after the lockdown periods. • Our proportional meta-analysis indicates the heterogeneous post-pandemic recovery patterns of each respiratory virus commonly identified in infants, where HRV was shown to be resilient whilst RSV was rapidly rebound.