Accidental allergic reactions to immediate‐type food allergens in Japanese children: A single‐center study

Abstract Background Few studies have assessed the nature of accidental allergic reactions (AAR). We assessed the prevalence and risk factors for AAR in Japanese children. Methods This study included children with immediate‐type hen's egg (HE), cow's milk (CM), wheat, or peanut allergy who developed allergic reactions within at least 2 years and were followed up regularly at a single national allergy center in Japan. From January to December 2020, low‐dose reactivity was defined as allergic reactions to ≤250, ≤102, ≤53, or ≤ 133 mg of HE, CM, wheat, or peanut protein, respectively. The annualized AAR rate showed the number of reactions per patient per year (95% confidence interval). AAR risk factors were analyzed using multiple logistic regression. Results Of the 1096 participants, 609, 457, 138, and 90 had HE, CM, wheat, and peanut allergies, respectively. The median (interquartile range) age was 5.0 (2.3–8.6) years, 39% had completely eliminated allergenic food, and 24% had low‐dose reactivity. The annualized AAR rate was 0.130 (0.109–0.153) in all sub‐cohorts. Moderate and severe symptoms occurred in 50% and 0.7%, respectively, of children who experienced AAR. Multiple logistic regression revealed that low‐dose reactivity was a significant risk factor for AAR in the overall and CM cohorts, respectively ( p < .001 and p = .036). Conclusion In this single‐center study in Japan, the annualized AAR rate was relatively low during the COVID‐19 pandemic; however, half of the participants with AAR had moderate to severe symptoms. Especially in the case of low‐dose reactivity, children would require careful AAR risk management.