Infant Whole-Cell Versus Acellular Pertussis Vaccination in 1997 to 1999 and Risk of Childhood Hospitalization for Food-Induced Anaphylaxis: Linked Administrative Databases Cohort Study

BACKGROUND: Evidence suggests that children who had received an initial priming dose of whole-cell pertussis (wP) vaccine, rather than acellular pertussis (aP) vaccine, had a lower risk of developing IgE-mediated food allergy, the most common cause of anaphylaxis-related hospital presentations of childhood. OBJECTIVE: To assess the association between wP versus aP vaccination in infancy and subsequent hospital presentations for anaphylaxis. METHODS: This study was preregistered under PMID 34874968. Perinatal records for a cohort of New South Wales -born children (1997-1999) receiving their first dose of pertussis-containing vaccine before age 4 months were proba- bilistically linked to hospital and immunization records. We used adjusted Cox models to estimate hazard ratios (aHRs) and 95% CIs for anaphylaxis -coded hospitalizations. RESULTS: There were 218,093 New South Wales -born chil- dren who received a first dose of wP or aP before age 4 months. Among these children, 86 experienced at least one hospitaliza- tion for food -induced anaphylaxis at age 5-15 years (range of events per patient, one to three). The person -time of follow-up was 1,476,969 years, and 665,519 years for children vaccinated with wP as a first dose (wP-1 children) and aP as a first dose (aP- 1 children), respectively. The incidence rates for first hospitali- zation for food anaphylaxis were 3.5 (95% CI, 2.6-4.6) and 5.1 (95% CI, 3.5-7.1) per 100,000 child -years among wP-1 children and aP-1 children, respectively (aHR for wP vs aP = 0.47; 95% CI, 0.26-0.83). For first admission for venom anaphylaxis, the incidence rate was 4.9 (95% CI, 3.9-6.2) per 100,000 child -years among wP-1 children and 5.1 (95% CI, 3.5-7.1) per 100,000 child -years among aP-1 children (aHR for wP vs aP = 0.92; 95% CI, 0.53-1.60), and for all -cause anaphylaxis, the incidence rate was 10.6 (95% CI, 9.0-12.4) per 100,000 child -years among wP-1 children and 12.8 (95% CI, 10.2-15.8) per 100,000 child - years among aP-1 children (aHR for wP vs aP = 0.92; 95% CI, 0.53-1.60). CONCLUSION: Vaccination with wP in infancy was associated with a lower risk of hospitalizations for food -induced anaphy- laxis (and therefore severe IgE-mediated food allergy) occurring in childhood. (c) 2024 American Academy of Allergy, Asthma & Immunology (J Allergy Clin Immunol Pract 2024;12:670-80)