Pediatric respiratory co-infection and immunologic response: peds recon study protocol

Background: Acute Viral Respiratory Infections (AVRIs) from SARS-CoV-2, influenza, and RSV are major causes of pediatric illness, yet little is known about how non-medically attended infections influence immune development. Understanding early-life AVRIs patterns and their impact on the developing mucosal immune system is essential to inform interventions that improve long-term child health. Methods: This ongoing prospective observational cohort study, initiated in January 2024, investigates respiratory viral infections, co-infections, and their effects on immune responses in children aged 1 month to 17 years. Participants are followed for two years, with data collected at baseline (when healthy) and during acute visits (when symptomatic). At baseline, nasopharyngeal swabs and blood samples are collected for viral screening and immune analysis. During acute visits, swabs are collected for viral detection and immunologic assays. If SARS-CoV-2, influenza, or RSV is detected, a post-acute visit occurs 10–21 days after symptom onset for repeat swabs and blood collection. The primary outcome is to define age-based immune responses and assess how co-infections influence immune regulation. Discussion: This study captures the full spectrum of pediatric AVRIs, including non-medically attended illnesses, to address gaps in immune development research. Findings may inform strategies to optimize prevention and treatment across childhood. Impact: Acute viral respiratory infections are the most common cause of childhood morbidity and mortality; however, they are frequently non-medically attended, leaving critical gaps in our understanding. Co-infections with respiratory viruses such as SARS-CoV-2, influenza, and respiratory syncytial virus (RSV) may alter immune responses, but their impact on long-term immunity remains poorly understood. Understanding age-dependent patterns of respiratory viral infections and co-infections will provide critical insights into immune development and potential vulnerabilities in pediatric populations. This study aims to define age-based differences in immunity in the respiratory track in response to respiratory viral pathogens and examine the impact of co-infection on immune regulation.