Age-dependent clinical and molecular rhinovirus epidemiology, 2018 to 2023

OBJECTIVES: Respiratory viruses show different circulation patterns. While influenza and respiratory syncytial virus epidemiology is well documented, the epidemiology of other respiratory viruses is less reported. METHODS: We studied respiratory virus epidemiology in Southern France from 2018 to 2023 focusing on rhinovirus epidemiology in relation to age as well as molecular epidemiology of rhinoviruses circulating during the 2022 and 2023 autumn peaks. RESULTS: Rhinoviruses were the most frequently detected respiratory viruses. A part from 2020, rhinoviruses exhibited two waves per year, with a nadir in summer. During the SARS-CoV-2 epidemic, respiratory virus circulation was reduced from weeks 14 to 25 of 2020. Interestingly, rhinoviruses were the first to recirculate substantially. Rhinovirus peaks in children younger than three years mostly preceded the peaks in adults. Wave-driving relative risk calculations suggest that young children contribute more than adults to rhinovirus epidemics, except during the COVID-19-related countermeasures. The rhinovirus autumn peaks were caused by 27 and 23 genotypes in 2022 and 2023, respectively. CONCLUSIONS: The circulation of rhinoviruses is predominant in children throughout the year. Their peaks are caused by high genotypic diversity. The SARS-CoV-2 pandemic had an impact on the circulation of rhinoviruses, but to a lesser extent than on the other respiratory viruses.