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Young boy getting vaccine

Study: 17% of toddlers don’t finish all vaccine series they started

July 25, 2023

About 17% of toddlers who started seven recommended vaccine series did not complete one or more, according to a new study.

Authors said logistical barriers are more likely to be the cause than parental hesitancy and urged action.

“Increased focus on strategies to encourage multi-dose series completion is needed to optimize protection from preventable diseases and achieve vaccination coverage goals,” they wrote in “Failure to Complete Multidose Vaccine Series in Early Childhood,” (Michels SY, et al. Pediatrics. July 25, 2023).

Researchers analyzed data from the 2019 National Immunization Survey-Child on a nationally representative sample of just over 16,000 children ages 19-35 months. They looked at seven multidose vaccines given to young children — four doses of diphtheria, tetanus and acellular pertussis (DTaP), four doses of pneumococcal conjugate vaccine (PCV), three to four doses of Haemophilus influenzae type b (Hib), three doses of hepatitis B (HepB), three doses of polio (IPV), one dose of measles, mumps and rubella (MMR) and one dose of varicella (VAR) vaccines.

About 73% of toddlers completed all seven series, while about 10% did not initiate one or more, according to the study. The most common not to be initiated were VAR and MMR, which are recommended later than the other vaccines. About 1% of children did not receive any vaccines.

Researchers focused on the 17% of children who initiated all seven series but did not complete one or more. The most common incomplete series after initiation were Hib, PCV and DTaP. About 47% of this group were just one dose short of completing all seven series.

Children who moved to a different state were less likely to complete a series, which may have been due to delays in establishing a new medical home or missing records, according to the study.

Having an incomplete series also was linked to not having health insurance and living in a lower income household or rented home. Black children were more likely to be missing a vaccine dose in a series than White children.

“Pediatric health equity cannot be achieved without increasing support for low-income children and children from racial minority groups, who, as most recently highlighted by the COVID-19 pandemic, are most at-risk for infectious diseases and poorer outcomes due to social and environmental determinants of health,” authors wrote.

Previous studies have found vaccine hesitancy is more common in not initiating a vaccine series than starting but failing to complete a series. Those who did not finish a series likely faced structural barriers. Authors encouraged increased use of reminder systems, flexible scheduling and planning before a visit. Clinicians also can help eligible low-income children enroll in the Vaccines for Children program.

“Renewed efforts to better support timely completion of multidose vaccine series in early childhood are needed to achieve vaccination coverage goals,” authors wrote.



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