August 07, 2019
2 min read

More than half of preterm infants undervaccinated at age 19 months

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Photo of Annika Hofstetter
Annika M. Hofstetter

Research published in Pediatrics suggested that more than 50% of infants born preterm in Washington State did not receive all recommended vaccinations in the seven-vaccine series by age 19 months. Preterm infants were also less likely than term infants to be fully vaccinated by age 36 months.

Study researcher Annika M. Hofstetter, MD, PhD, MPH, an assistant professor of pediatrics at the University of Washington, told Infectious Diseases in Children that several factors could help explain why preterm infants are undervaccinated.

“Likely, there are parent-, provider- and system-based factors that play a role,” she said. “For example, earlier studies suggest that some parents and providers may be unaware of the vaccine recommendations for preterm infants. In addition, many preterm infants have complex health care needs, and their health care utilization patterns may differ from those of term infants. They may have fewer health supervision visits with their primary care provider or may have competing priorities during those visits.”

The researchers retrospectively analyzed data on a cohort of infants (n = 10,367) born in Washington state between 2008 and 2013 at an urban academic medical center. Electronic health records were linked with vaccine data pulled from the Washington State Immunization Information System to determine the number of infants who completed the recommended vaccine series by age 19 months.

Approximately 19% of the infants included in the study were born preterm. Preterm infants were less likely to complete the seven-vaccine series compared with term and post-term infants by age 19 months (47.5% vs. 54%; adjusted OR = 0.77; 95% CI, 0.65-0.9) and 36 months (63.6% vs. 71.3%; aOR = 0.73; 95% CI, 0.61-0.87).

Baby on Tummy 
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Very preterm infants born at 23 to 33 weeks’ gestation and late preterm infants born at 34 to 36 weeks’ gestation were less likely to receive the seven-vaccine series by age 19 months compared with term and post-term infants. Full influenza vaccination coverage by age 19 months also varied among the groups (early preterm = 47.7%; late preterm = 41.5%; term/post-term = 44.7%; P = .02).

“Pediatricians should check vaccination status and offer needed vaccines at all clinical encounters, including in diverse health care settings such as subspecialty clinics or in the hospital,” Hofstetter said. “They could also consider other evidence-based strategies in their practice, such as reminder-recall systems, to increase vaccination coverage in this high-risk population.”

In addition, Hofstetter said that pediatricians should “strongly recommend” vaccination and address any concerns brought up by the family.

“They should emphasize that preterm infants are at particularly high risk for serious vaccine-preventable diseases and that timely vaccination is critical for optimal protection,” she said. – by Katherine Bortz

Disclosures: Hofstetter reports receiving research support from the Pfizer Independent Grants for Learning and Change. Please see the study for all other authors’ relevant financial disclosures.