D1.476 - Impact of neonatal vaccination on the incidence of atopic dermatitis in children by 36 months: a prospective cohort study

The continued increase in the prevalence of allergic diseases in children in recent decades has coincided with the expansion of routine immunization programs. This trend has heightened public concern about a potential link between immunization and the rise in allergies, leading to reduced vaccine uptake in some regions. However, clinical evidence suggests that early neonatal immunization acts as a protective factor, promoting a shift from a Th2-dominant neonatal immune profile toward a Th1-dominant response, potentially reducing allergic sensitization. The aim of this study was to evaluate the potential association between neonatal immunization (BCG-M and Hepatitis B) and the development of atopic dermatitis (AD).

We analyzed individual medical records of 2,279 children born between 2018 and 2022, followed longitudinally through the first 36 months of life. The study monitored the frequency of various anamnestic risk factors and confirmed cases of AD. We evaluated vaccination status (timely BCG-M and Hepatitis B vaccination according to the National Immunization Schedule) alongside several key predictors: aggravated family history of allergy, type of delivery, prematurity, and maternal antibiotic use during pregnancy.

Of the 2,279 children, 2,055 (90,2%) received the BCG-M vaccine and 2,016 (88,5%) were vaccinated against Hepatitis B. During the 36-month follow-up, 454 children (19,9%) developed AD. The incidence was significantly higher in preterm infants compared to full-term children (32,1% versus 19,6%, p=0,002) and in those born via cesarean compared to vaginal delivery (16,7% versus 12,3%, p=0,014). Positive medical family history was the strongest predictor of disease (79,9% versus 15,6%, p<0,001). Maternal antibiotic use showed borderline significance (26,9% versus 19,6%, p=0,065). Data regarding individual vaccines showed no statistically significant impact on AD frequency; specifically, no significant difference was observed for BCG-M (20,6% versus 14,8%, p=0,168) or Hepatitis B vaccination (20,3% versus 16,7%, p=0,104). Most importantly, combined vaccination did not lead to an increase in disease incidence (15,8% versus 20,6%, p=0,078), confirming that neonatal immunization does not increase the risk of AD.

Our findings align with existing evidence, confirming that vaccination does not increase the risk of AD. Early-onset AD is primarily driven by genetic predisposition and delivery mode, while routine immunization remains a safe practice. These findings may facilitate adherence to vaccination among both health workers and patients.