Epidemiology of Symptomatic Respiratory Viral Codetections Among Children and Adults in the Cascadia Community-Based Cohort, 2022-2024
Abstract
Background: Respiratory virus codetection, or the concurrent presence of multiple viruses in a single host, can complicate diagnoses and may influence clinical severity. This study examined the burden and clinical impact of viral codetections in a community-based U.S. cohort, focusing on eight common respiratory pathogens, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza virus (Flu), respiratory syncytial virus (RSV), and others. Methods: We conducted a secondary analysis of data from the CASCADIA study, a prospective cohort of 3,500 participants aged 6 months to 50 years, followed from June 2022 to March 2024. Illness episodes with single vs. multiple virus detections at illness onset were compared in terms of demographic and clinical characteristics. Multivariable logistic regression models were used to assess the association between codetection and illness severity outcomes, including extended symptom duration, medically attended illness, and absenteeism. Analyses were conducted both overall and stratified by involved viral pathogens and age groups. Results: Among 8,908 symptomatic illness episodes, 9.6% involved codetection. Codetections were most frequent in children aged 5-11 years, while single detections were more common in adults. Overall, codetection was not significantly associated with illness severity. However, in children, codetection was linked to higher odds of extended symptoms (aOR: 1.27; 95% CI: 1.06–1.53) and medical visits (aOR: 1.53; 95% CI: 1.17–1.99). A positive, though non-significant, association was observed with absenteeism in adults. Conclusion: Although most associations between codetection and illness severity were not statistically significant, some patterns suggest potential links to more severe outcomes, particularly in pediatric populations. Further research is needed to better understand viral interactions and their influence on clinical trajectories over time.