Atopic outcomes at 5 years in the CORAL cohort born during the 2020 COVID-19 lockdown

The 2020 SARS-CoV-2 lockdown in Ireland was among the most stringent in Europe. The CORAL (Impact of Coronavirus Pandemic on Allergic and Autoimmune Dysregulation in Infants Born during Lockdown) study was developed to investigate early-life allergic outcomes in an altered environment. At 2 years we showed lower food allergy and higher atopic dermatitis rates. The current report reassesses this same cohort at 5 years to evaluate whether early pandemic-related trends were transient or represented enduring alterations in childhood allergy.

This longitudinal observational study assessed outcomes at 5 years. Clinical assessments included evaluation of atopic dermatitis, skin prick testing for food and aeroallergens, and collection of stool and blood samples. Parent-completed questionnaires collected data on environmental and household exposures, allergic and respiratory outcomes, and healthcare use.

Aeroallergen sensitisation increased from 8.9% at 2 years to 24% at 5 years (p < .001). Sensitisation strongly predicted allergic rhinitis symptoms (OR 5.68, p < .001). Parent-reported wheeze was unchanged between 2 years (23.8%) and 5 years (22.1%) and strongly associated with asthma diagnosis (χ² = 33.0, p < .001). Wheeze occurred predominantly in children with a recent infection. Most atopic dermatitis had resolved and food allergy remained uncommon at 5 years of age.

This study provides the first longitudinal evaluation of pandemic-associated early-life exposures and atopic outcomes in children. Our findings suggest that pandemic-associated early-life environmental changes may have selectively modified food allergy risk, while the overall pattern of allergic disease remained broadly consistent with the accepted evolution of allergic conditions.