Pharmacovigilance analysis of vaccination errors during pregnancy using VAERS data.

BACKGROUND/

OBJECTIVE

Vaccination during pregnancy protects both pregnant individuals and infants, yet real-world data on administration errors in this population are limited. We aimed to identify and characterize safety signals for vaccination errors during pregnancy using the Vaccine Adverse Event Reporting System (VAERS).

METHODS

We conducted a retrospective analysis of VAERS reports from January 1, 2023, to May 30, 2025, involving vaccinations administered during pregnancy. Disproportionality was assessed using PRR (>2), ROR (signal if lower 95% CI > 1), EB05 (>2), and IC025 (>0) for error types with ≥5 reports.

RESULTS

Of 171,958 unique VAERS reports, 1413 involved vaccinations during pregnancy. Several vaccine-error pairs showed moderate to strong signals: RSV-wrong product (PRR 6.8; ROR 10.3, 95% CI 7.4-14.6; EB05 1.8; IC025 0.8), TDAP-extra dose (PRR 9.7; ROR 11.6, 95% CI 6.7-20.3; EB05 3.0; IC025 1.6), TDAP-storage error (PRR 15.4; ROR 17.7, 95% CI 8.5-36.6; EB05 3.2; IC025 1.7), and influenza-expired product (PRR 8.3; ROR 8.8, 95% CI 3.4-22.4, EB05 1.8; IC025 0.9). Live vaccine administrations (MMR n = 35, varicella n = 42) were reported, with 47.6% unaware of pregnancy at vaccination. No birth defects or deaths were reported among vaccine-error pairs.

CONCLUSIONS

Vaccine administration during pregnancy showed disproportionate reporting of specific errors, especially RSV-wrong product, multiple TDAP-related errors (extra dose, storage) and live vaccine administration, with no severe outcomes reported. Findings suggest practical targets for error prevention to reduce wrong-product and scheduling errors while maintaining access to indicated maternal immunizations.