Preterm infants are likely to be undervaccinated

Preterm infants may face an increased risk for infections that are vaccine-preventable along with associated complications. A new study published in Pediatrics indicates that preterm infants may also be at risk of not being vaccinated in a timely manner.

Researchers used infants in Washington State who had birth hospitalizations at an urban academic medical center between 2008 and 2013. They connected demographic, clinical, and visit data pulled from electronic health records to vaccine data from the Washington State Immunization Information System. They compared the completion of the recommended 7-vaccine series by age 19 months between preterm (born at <37 weeks’ gestation) and term/postterm infants (born at 37-43 weeks’ gestation). They also looked at whether the series was completed by age 36 months and which vaccines in the series were received. Researchers also looked at rotavirus, hepatitis A, and influenza immunizations.

The cohort included 10,367 infants, of which 19.3% were born prematurely. The preterm infants had lower 7-vaccine series completion at 19 months than their term/postterm counterparts (47.5% vs 54.0%, respectively; adjusted odds ratio, 0.77 [95% confidence interval, 0.65-0.90]). Similarly, at 36 months, preterm infants had a lower completion rate than those who were born at term and postterm (63.6% vs 71.3%, respectively; adjusted odds ratio, 0.73 [95% confidence interval, 0.61–0.87]). Both early preterm (23-33 weeks’ gestation) and late preterm (34-36 weeks’ gestation) infants had lower rates of 7-vaccine series completion when compared with those born term or postterm. Influenza vaccination coverage by age 19 months differed between the groups as well (early preterm, 47.7%; late preterm, 41.5%; term/postterm, 44.7%; P=.02).

The researchers concluded that more than 50% of preterm infants were undervaccinated at age 19 months and that roughly one-third of that group would not have caught up on vaccinations by age 36 months. They said that strategies to improve vaccinations are needed.