There should be no hesitation in administering the routine vaccination schedule for 13-valent pneumococcal conjugate vaccine (PCV13) on account of gestational age or birth weight in preterm infants, researchers concluded.

In a phase IV study, researchers compared 100 term with 100 preterm infants; both groups were vaccinated on the routine schedule at ages 2, 3, 4, and 12 months. After the 12-month (toddler) dose of the PCV13, the infants were evaluated for serum antibody persistence at 12 and 24 months. “To date, no studies have examined the long-term persistence of immune responses to PCV13 in formerly preterm infants,” noted Federico Martinón-Torres, MD, PhD, of Hospital Clínico Universitario de Santiago de Compostela, Spain, and his coauthors.

In the study, at six sites in Spain and five sites in Poland between October 2010 and January 2014, both groups were checked for geometric mean concentrations of serotype-specific anticapsular immunoglobulin G binding antibodies and for opsonophagocytic activity. All 200 subjects were white and were generally healthy; the preterm infants were grouped by gestational age at birth of less than 29 weeks (n = 25), 29 weeks to less than 32 weeks (n = 50), or 32 weeks to less than 37 weeks (n = 25). Twelve subjects dropped out of the study by the first year’s evaluation, and another eight of the term subjects and seven of preterm subjects dropped out by the second year’s evaluation ( Ped Infect Dis J. 2017. doi: 10.1097/INF.0000000000001428 ).

At both follow-up time points, no discernible patterns were observed in IgG GMCs for any serotype or in opsonophagocytic activity geometric mean titers across preterm subgroups based on gestational age.

“The vaccination phase of the study demonstrated that preterm infants are able to generate an immune response to PCV13 that is likely to protect against invasive pneumococcal disease. However, IgG GMCs were lower in preterm than term infants for nearly half of the serotypes at all time points. Antipneumococcal IgG levels in preterm infants were generally lower than in term infants, but fewer differences in opsonophagocytic activity were seen between the groups,” Dr. Martinón-Torres and his associates reported.

They concluded by recommending “timely vaccination of infants against Streptococcus pneumoniae starting at the chronologic age of 2 months, regardless of gestational age or weight at birth,” and “giving the toddler dose at the earliest possible opportunity.”

Pfizer funded the study. Dr. Martinón-Torres reported receiving research grants and/or honoraria as a consultant/adviser and/or speaker and for conducting vaccine trials for GlaxoSmithKline, MedImmune, Merck, Novartis, Pfizer/Wyeth, Sanofi Pasteur, and the Carlos III Health Institute. Several coauthors disclosed ties with pharmaceutical companies; four are stock-holding employees of Pfizer and another is an employee of a company contracted by Pfizer.