Premature babies face a higher risk of infections that can be prevented with vaccines, but many fall behind in getting immunized and fail to catch up months later, new research shows.

Early and late preterm infants had a lower rate of completion of a 7-vaccine series, compared with full-term and post-term children at 19 months and 36 months, according to a study released Wednesday.

“It is important for parents and providers to know that many preterm infants have not received all recommended vaccines and, thus, are inadequately protected against serious vaccine-preventable diseases,” said Dr. Annika Hofstetter of the Seattle Children’s Research Institute, who led the study. “We need to improve timely vaccine uptake in this population in order to ensure optimal protection.”

Dr. Hofstetter, an assistant professor of pediatrics at the University of Washington, said all infants, including premature babies, should be vaccinated.

“In general, preterm infants should receive vaccines at the same chronological age and according to the same schedule as term infants,” she told The Washington Times.

Her study was published Wednesday in Pediatrics: Official Journal of the American Academy of Pediatrics.

In the study, researchers examined the health records of 10,367 infants born at an urban academic medical center in Washington state between 2008-2013. About 1 in 5 — or 2,073 — were born prematurely.

More than half of the preterm infants were undervaccinated at 19 months, and a third failed to complete vaccinations at 36 months, the researchers found. About 53% of preterm infants did not receive all their vaccinations compared to 46% term and post-term infants.

The 7-vaccine series includes four doses of diphtheria-tetanus-pertussis (DTaP) vaccine, three doses of poliovirus vaccine, one dose of the measles-mumps-rubella (MMR) vaccine, three doses of Haemophilus influenza type b vaccine, three doses of the hepatitis B vaccine, one dose of the varicella vaccine and four doses of the pneumococcal conjugate vaccine (PCV).

Fewer pre-term infants received each vaccine in the 7-vaccine series by 19 months compared to term and post-term babies, excluding the MMR and varicella vaccines where the researchers observed no difference.

Dr. Lakshmi Katakam, a neonatal specialist at the Texas Children’s Hospital, said the study’s findings do not surprise her, noting how parents of premature infants are often concerned that the babies are too fragile, too young or too small to be vaccinated.

“It is true they are very young, they’re fragile and they’re small. But that means they are very susceptible to acquiring infections. So it’s even more important that they have the protective effects of a vaccine,” said Dr. Katakam, who was not involved in the study. Because of their underdeveloped immune systems, premature infants are at increased risk of being infected and having more severe symptoms, she said, adding that being born prematurely doesn’t result in being intolerant to vaccines.

Possible reasons for undervaccination of premature infants could be safety concerns around vaccines and the perception that preterm babies are not developed enough for them, worry from providers about vaccine adverse events immediately after immunization and limited knowledge of and adherence to vaccine recommendations, the study outlines.

The researchers also analyzed vaccination rates for the rotavirus vaccine, hepatitis A vaccine and the influenza vaccine.

While rotavirus vaccination coverage was lower among premature infants, immunization rates for influenza were similar for preterm, full-term and post-term babies, the study says.

Early pre-term infants had particularly low hepatitis B and rotavirus vaccination coverage. “All preterm infants, regardless of their degree of prematurity, were vulnerable to undervaccination,” the study says. “These findings are worrisome given the increasing prevalence of preterm births and the fact that preterm infants are particularly susceptible to vaccine-preventable diseases.”

Dr. Katakam said it’s important to be mindful of who comes in contact with preterm infants including hospital staff and visiting family members and to make sure they are also protected against vaccine-preventable diseases.

About 1 in 10 infants in the U.S. was born prematurely in 2017, according to the Centers for Disease Control and Prevention.

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