Earlier egg introduction guidelines linked to measurable decline in infant egg allergy prevalence

A guideline update recommending earlier introduction of egg into the infant diet has been associated with a measurable population-level decline in egg allergy among 1-year-old infants, according to a cross-sectional study published in JAMA Pediatrics.¹ The findings offer some of the first population-based evidence that food allergy prevention guidelines, when effectively implemented, can translate into real-world reductions in allergy burden.

"These findings suggest that food allergy prevention guideline updates informed by randomized trial evidence may be associated with a reduction in food allergy prevalence when implemented effectively," wrote the authors of the study.¹

Study design: Comparing egg allergy before and after Australian guideline change

The investigators compared 2 population-based cohorts of infants aged 11 to 15 months, 5,276 infants recruited from 2007 to 2011 (the HealthNuts study) and 1,933 recruited from 2018 to 2019 (the EarlyNuts study), using identical recruitment methods at 12-month immunization centers in Melbourne, Australia.¹ The 2007–2011 cohort predated Australia's 2016 allergy prevention guideline update, which began recommending the introduction of egg and other allergens in the first year of life.

Infants underwent skin prick testing to egg white; those with a detectable wheal underwent oral food challenge (OFC) to raw egg.¹ Egg allergy was defined as a positive OFC result, a recent reaction consistent with OFC-stopping criteria, or anaphylaxis in infants with a skin prick test wheal of at least 2 mm. To isolate the effect of the guideline change from demographic shifts between the 2 cohorts, investigators used direct regression standardization to adjust for known allergy risk factors—including parent country of birth, number of siblings, family history of food allergy, preterm birth, pet dog ownership, and early eczema.¹

Egg introduction timing more than doubled after guideline update

The proportion of infants introduced to egg by 6 months of age more than doubled between cohorts, rising from 25.4% in 2007–2011 to 57.3% in 2018–2019.¹ The median age at egg introduction fell from 8 months to 6 months over the same period.

Uptake was broad across demographic subgroups, though the increase was somewhat smaller in families with parents born in East Asia, who also carried a nearly threefold higher baseline risk of egg allergy compared with families of Australian-born parents.¹ The authors noted this disparity signals a need for targeted outreach to reach higher-risk communities.

Egg allergy prevalence declined 17.7% after risk factor adjustment

After adjusting for temporal changes in population demographics and known allergy risk factors, the prevalence of egg allergy in the 2018–2019 cohort was estimated at 7.6% (95% CI, 6.2%–9.0%), compared with 9.2% in the 2007–2011 cohort—an adjusted absolute decrease of 1.6 percentage points (95% CI, 0.005–3.3; P = .04), corresponding to a 17.7% relative decline.¹

The most striking reduction was seen among infants with early eczema, a high-risk group. Egg allergy prevalence in this subgroup fell from 34.6% to 21.9% after adjustment—an absolute decrease of 12.7 percentage points (95% CI, 5.4–20.0; P < .001).¹ By contrast, infants without early eczema showed no meaningful change (adjusted absolute difference, 0.0 percentage points).

These eczema-stratified findings are consistent with prior randomized trial evidence: 2 RCTs that demonstrated a significant reduction in egg allergy with earlier introduction both recruited infants with eczema as an eligibility criterion.¹ The authors suggest early allergen introduction may exert its greatest protective effect in this high-risk population, helping to explain why population-level reductions are more modest than those seen in highly selected clinical trial cohorts.

Population impact smaller than clinical trial projections—and why that matters

The 2018–2019 EarlyNuts study was powered to detect a 30% relative reduction in egg allergy based on RCT effect sizes—yet the observed adjusted reduction was closer to 18%.¹ A similar pattern emerged for peanut allergy using the same methodology: a previously reported modest reduction from 3.1% to 2.6% fell short of trial-based predictions.

This divergence reflects a well-documented gap between efficacy in clinical trials and effectiveness in general populations. Trial participants often receive additional support to facilitate allergen introduction on schedule and represent a selected group with different risk profiles.^1,2 In community settings, uptake—while substantially improved in Australia—remained incomplete, and factors such as ingestion frequency (not captured in the 2007–2011 cohort) may further modulate risk.

For comparison, US data from 2021 found that only 15.5% of infants were introduced to eggs before 7 months of age, suggesting that implementation infrastructure matters.¹ Programs such as Australia's Nip Allergies in the Bub initiative and routine engagement with maternal-child health nurses were cited as possible contributors to the notably higher uptake observed in the Australian setting.

Limitations and next steps

Several limitations warrant consideration. Participation in skin prick testing in the 2018–2019 cohort was lower (73.4%) than in the 2007–2011 cohort (97.2%), largely because many families declined testing when their infant was already tolerating allergenic foods—a finding the authors note is unlikely to introduce meaningful bias.¹ Data on egg introduction timing were collected retrospectively and may be subject to recall bias. The frequency of egg ingestion—which may contribute to allergy prevention independently of timing—could only be assessed in the more recent cohort. And as with all observational analyses, residual confounding from unmeasured risk factors cannot be excluded.

References

1. Koplin JJ, Shifti DM, Soriano VX, et al. Egg allergy prevalence before and after guidelines for earlier egg introduction. JAMA Pediatr. Published online June 8, 2026. doi:10.1001/jamapediatrics.2026.2080

2. Tan YY, Papez V, Chang WH, Mueller SH, Denaxas S, Lai AG. Comparing clinical trial population representativeness to real-world populations: an external validity analysis encompassing 43,895 trials and 5,685,738 individuals across 989 unique drugs and 286 conditions in England. Lancet Healthy Longev. 2022;3(10):e674-e689. doi:10.1016/S2666-7568(22)00186-6