A lower incidence of egg and peanut allergy was observed at 2 years despite greater prevalence of both atopic dermatitis (AD) and egg sensitization by the 12-month mark, according to a recent research letter.¹

This study—involving the CORAL cohort—studied infants born in Ireland at the time of the first COVID-19 lockdown between March and May 2020.

The team compared the allergy-related outcomes recorded in their research with the pre-pandemic BASELINE cohort recruited in the period between 2008 and 2011.²

The investigators hypothesized that these infants would likely have increased rates of allergy potentially due to their social and physical environment changes occurring during the pandemic.

The study was authored by Sadhbh Hurley, MB, from Paediatrics and Child Health at the Royal College of Surgeons Ireland.

“We hypothesized that infants born during this time would have increased rates of allergy possibly mediated through changes in the infant social and physical environment during the lockdown,” Hurley and colleagues wrote. “In this letter, we outline the unexpectedly low incidence of peanut and egg allergy at 2 years despite higher levels of atopic dermatitis…and egg sensitization at 12 months.”

Background and Study Results

The investigators used Food Frequency Questionnaires (FFQs) after 12 and then 24 months for the CORAL cohort, with the families of the infant participants being given standard weaning advice—and regularly being briefed—on maintenance strategies for allergenic foods such as peanuts and eggs.

The infants involved in CORAL were regularly brought to their primary care physician and public health nurse appointments for development checkups, vaccines, and briefings on allergenic food weaning.

The team managed to maintain a total of 320 infants for the study over the full 2-year study length, with 292 receiving skin prick tests to eggs, peanuts, and cow’s milk regardless of history.

The infants in the CORAL cohort had skin prick tests completed if they had clinical histories which were consistent with IgE-mediated food allergy, and they were reported to be food-sensitized if their skin prick test was found to be ≥3 mm.

The team decided upon allergy’s definition after 1 year being both an infant’s history of instant reaction to allergen or a positive oral food challenge (OFC) for the infants involved in the study, whereas at 2 years allergy was described as positive OFC.

The team found that in the time frame between 12 and 24 months of age in the BASELINE cohort, sensitization to peanuts doubled.

A major finding by the research team was that AD was higher for the CORAL cohort, but sensitization to peanuts and egg/peanut allergies were found to have decreased substantially by 24 months.

The investigators described their view that this may be thanks to the combined effect of the widely-adopted early introduction of the allergens and the infants’ encouraged, consistent consumption of peanuts.

They also attributed the incidence of egg allergies by the cohort at 2 years potentially being attributed to baked egg ladder-usage by those infants with reported allergies to egg.

“The potential importance of regular consumption is not yet widely appreciated outside the allergy specialist field; a recently published rostrum of international infant feeding guidelines highlighted the need for further research to clarify the necessary frequency and quantity of peanut to maintain tolerance,” they wrote. “We want public health strategies to include more emphasis on regular peanut consumption after the now widely adopted early introduction of peanut.”

References:

1. Hurley, S., Franklin, R., Murray, D., Venter, C. and O’B Hourihane, J. (2023), Changes in food sensitization with changing allergy practice in Ireland. Clin Exp Allergy. https://doi.org/10.1111/cea.14288
2. Sinéad M O’Donovan, Deirdre M Murray, Jonathan O’B Hourihane, Louise C Kenny, Alan D Irvine, Mairead Kiely, Cohort profile: The Cork BASELINE Birth Cohort Study: Babies after SCOPE: Evaluating the Longitudinal Impact on Neurological and Nutritional Endpoints, International Journal of Epidemiology, Volume 44, Issue 3, June 2015, Pages 764–775, https://doi.org/10.1093/ije/dyu157.