NEW research reveals that 15% of children aged 0–35 months in the USA received at least one invalid vaccine dose between 2011–2020.
The study analysed provider-verified vaccination records from the 2011–2020 National Immunization Survey–Child, a nationally representative dataset. Researchers quantified the prevalence of invalid vaccine doses (those given outside Advisory Committee on Immunization Practices (ACIP)-recommended minimum and maximum ages or intervals), by survey year and vaccine type.
The authors used logistic regression models to identify factors associated with invalid doses, such as demographic and geographic variables. They also assessed whether children who received invalid doses completed their vaccine series with the recommended number of valid doses by receiving extra vaccinations.
Out of 161,187 children surveyed, 22,209 (15.4%, 95% CI: 15.0–15.8%) had received at least one invalid vaccine dose. Of these, nearly half (44.9%, 95% CI: 43.2–46.6%) ultimately received additional doses to complete the series with the recommended number of valid vaccinations.
The highest rate of invalid dosing was observed for the three-dose rotavirus vaccine, affecting 4.4% of children, primarily due to the first dose being administered after the maximum allowable age (3.1%). Encouragingly, the overall percentage of children receiving invalid doses decreased from 16.9% in 2011 to 12.5% in 2020.
Certain factors were linked to an increased likelihood of invalid vaccinations. Children who moved across state lines had a 50% higher chance of receiving an invalid dose (adjusted odds ratio: 1.5, 95% CI: 1.4–1.6), highlighting the challenges of maintaining vaccination accuracy in mobile populations.
The study’s authors urge clinicians to remain vigilant in adhering to ACIP guidelines and ensure accurate documentation of vaccination schedules.
Ada Enesco, EMJ
Reference
Albers AN et al. Invalid vaccine doses among children aged 0 to 35 months: 2011 to 2020. Pediatrics. 2025;DOI:10.1542/peds.2024-068341.
