Did children's symptoms and infections decline during the COVID-19 pandemic? A comparison of parental reports before and during the pandemic from a birth cohort study in New Hampshire, USA.

Background: Restrictive measures were widely introduced at the start of the COVID-19 pandemic to reduce the spread of the virus. These restrictions have been linked to reductions in laboratory-diagnosed infections and hospitalisations. It is unclear if the observed decreases reflect a reduction in health-seeking behaviour or results from fewer infections per se. Methods: We have explored trends in caregiver reports of respiratory infections and symptoms needing a doctor visit in children aged 0-11 years using data from the New Hampshire Birth Cohort Study in 2011-2021, comparing the prepandemic and pandemic periods. Generalized Estimating Equations were used to model pandemic/prepandemic risk ratios (RRs) with adjustment for maternal and child characteristics. Results: The overall probability of a report of an upper respiratory tract infection (RTI) needing a doctor visit in children aged 0-11 years was 16.7%. There was strong evidence of a decline during the pandemic: 17.9% pre pandemic versus 8.19% in the pandemic period, adjusted RR 0.51 (95% CI: 0.42 to 0.64). Similar trends were seen for any lower RTI, any respiratory symptom and any other acute symptom with overall probabilities of 4.33%, 24.8% and 13.8%, respectively, and adjusted rate ratios 0.61 (0.41 to 0.91), 0.59 (0.51 to 0.68) and 0.72 (0.59 to 0.87), respectively. In contrast, respiratory syncytial virus and bronchiolitis remained steady. Conclusions: The steep decline in caregiver-reported infections and symptoms mirrored trends reported in laboratory-diagnosed infections and hospitalisations and suggests a real decrease in prevalence. Longer follow-up is needed to determine later consequences of the reduction in childhood infections.