HealthDay News — The immunogenicity of 13-valent pneumococcal conjugate vaccine (PCV13) is not significantly different for most serotypes when administered according to four different primary immunization schedules, researchers have found.
There were no significant differences in geometric mean concentrations (GMCs) of immunoglobulin G (IgG) antibodies among healthy term infants aged 1 year who were administered primary doses of PCV13 at months 2, 4 and 6; at months 2,3 and 4; at months 3 and 5; or at months 2 and 4, Judith Spijkerman, MD, of the University Medical Center in Utrecht, Netherlands, and colleagues reported in the Journal of the American Medical Association.
Since the infant pneumococcal vaccine was first introduced in 2000, many countries have incorporated it into routine pediatric immunization programs, albeit using different schedules. Debate has continued over whether giving the initial dose at 3 months rather than 2 months, or administering a three-dose rather than a two-dose schedule, offers greater protection.
To determine whether one regimen is preferable over another in terms of immunologic protection, Spijkerman and colleagues randomly assigned 400 healthy infants to one of four predetermined vaccine schedules in a 1:1:1:1 ratio. All infants were administered a booster dose at 11.5 months.
The primary outcome measure was antibody geometric mean concentrations against PCV13-included serotypes, measured one month after the booster dose. Only minor differences in antigen GMCs were observed for the different schedules.
Antigen levels for serotype 18C were higher with the 2-4-6 schedule than with the 2-3-4 schedule (10.2 mcg/mL, 95% CI 8.2-12.7 vs. 6.5 mcg/mL, 95% CI 5.4-7.8) and also for serotype 23F (10.9 mcg/mL, 95% CI 9-13.3 vs. 7.3 mcg/mL, 95% CI 5.8-9.2).
For serotypes 6B, 18C, and 23F, the 2-4-6 schedule was superior to the 2-4 schedule. The 3-5 schedule was superior to the other schedules for serotype 1.The 3-5 schedule also produced similar antigen levels as the 2-4-6 schedule with lower levels observed only for serotypes 6A, B and 23F.
Nearly all infants had achieved the recommended protective cutoff of 0.35 mcg/mL
“Parents should not delay vaccinating their children to obtain a specific vaccine,” pediatrician Henry Bernstein, DO, a coauthor of the recommendations, said in a statement. “To induce the earliest possible protection against pneumococcal disease in the absence of herd immunity, accelerated immunization schedules including neonatal vaccinations are preferred.”
In an accompanying editorial, Katherine L. O’Brien, MD, of the International Vaccine Access Center at Johns Hopkins, echoed the importance of immunizing children early with an adequate number of doses.
“Emphasis on immunogenicity differences should not be separated from the larger context of protection at the individual levels, pneumococcal disease epidemiology, vaccine program performance, and ultimately clear measures of disease outcome,” O’Brien wrote.