Atopic outcomes at 2 years in the CORAL cohort, born in COVID‐19 lockdown

Abstract

IntroductionThe CORAL study is a cohort of infants born during the first weeks of the first SARS‐CoV‐2 (COVID‐19) lockdown. This cohort has had lower antibiotic exposure, higher breastfeeding rates and lower infection rates, especially in the first year of life. We hypothesized that the altered early‐life environment of infants born during lockdown would change the incidence of allergic conditions.MethodsThis longitudinal, observational study followed 365 infants born between March and May 2020 from enrolment to the age of 2 years. Infants attended three research appointments at 6‐, 12‐, and 24‐months and completed detailed questionnaires. At research appointments, children had skin prick testing, and atopic dermatitis (AD) assessment. Statistical analysis focused on changes within the group at different time points, the influence of specific environmental factors on allergic risk and compared the incidence of atopic conditions with a pre‐pandemic Irish infant cohort, BASELINE.ResultsAD was more common in CORAL group at both 12 (26.5% vs. 15.5%; p < .001) and 24 months (21.3% vs. 15.9%; p = .02) compared with pre‐pandemic BASELINE cohort. Within the CORAL group, those with AD at both 12‐ and 24‐month appointments had a more severe AD phenotype associated with a higher risk of allergic sensitization. There was less milk (0% vs. 1%; p = .09), peanut (0.6% vs. 1.8%; p = .3), and egg allergy (0% vs. 2.9%; p < .001) in the CORAL group at 24 months compared with the BASELINE cohort. Aeroallergen sensitization increased between 12 and 24 months in the CORAL cohort (1.5% vs. 8.9%; p < .001), as did parent‐reported wheezing episodes (9% vs. 24%; p < .001).ConclusionsDespite higher AD incidence in the CORAL cohort, the incidence of food sensitization and allergy are lower than expected pre‐pandemic rates possibly reflecting the early introduction and maintenance of dietary allergens enhanced by changes in infant infections, antibiotic use, and breastfeeding in the first 2 years of life in the group. These beneficial effects of the lockdown could be outweighing the expected risk of less early‐life microbial encounters outlined by the hygiene hypothesis.

Editorial Comment on “Atopic outcomes at 2 years in the CORAL cohort, born in COVID‐19 lockdown”

“…The SARS‐CoV‐2 pandemic in early 2020 prompted various lockdowns and stringent hygiene measures, offering an intriguing opportunity to investigate the impact of these altered environmental factors on the prevalence of atopic conditions. The CORAL study is a longitudinal observational project, following 365 infants born in Ireland, during the initial pandemic period (March–May 2020) from enrollment to 24 months of age 4 . The authors compared the occurrence of allergic diseases with a pre‐pandemic Irish cohort (BASELINE study 2008–2011) 5 .…”