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Newborn vaccination with pneumococcal conjugate vaccine promising
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Vaccinating children at birth with the seven-valent pneumococcal conjugate vaccine may be a viable way of providing early protection in countries who have a high disease burden, according to a speaker at the American Society for Microbiology’s 49th Interscience Conference on Antimicrobial Agents and Chemotherapy.
David Goldblatt, PhD, of the Immunobiology Unit at the UCL Institute of Child Health in London presented the results of the first trial to ever examine vaccine safety and immunogenicity in infants administered a first dose of seven-valent pneumococcal conjugate vaccine (PCV7, Wyeth) at birth compared with newborns administered a first dose at six weeks in accordance with WHO’s Expanded Program on Immunization (EPI). The study was conducted at the Kenya Medical Research Institute in Kilifi.
“Sixteen percent of deaths attributable to invasive pneumococcal disease in Kenya occur within the first few months of life and 23% of invasive pneumococcal disease occurs in the first three months of life,” Goldblatt said. “If we are trying to induce protection through vaccination and we only start at 6 weeks of life, we’re already missing the boat for a significant proportion of children.”
The researchers randomly assigned 300 infants to receive PCV7 at birth (n=150) or age 6 weeks (n=150). All infants received additional doses of PCV7 at weeks 10 and 14 with their EPI vaccines. At 36 weeks, half of each group received either another dose of PCV7 or a dose of pneumococcal polysaccharide vaccine (PPSV23, Pneumovax, Merck).
The following results were reported:
- Eighty-five percent or more of children in both groups achieved protective antibody titers greater than 0.35 mg/mL by 18 weeks.
- Patients vaccinated at six weeks had significantly higher immunoglobulin G geometric mean titers for serotypes 4, 6B, 18C and 19F at 18 weeks, and for serotype 4 at 36 weeks.
- Despite lower titers at 18 weeks of age, the avidity of the antibody specific for serotype 4 was of higher avidity in the newborn group when measured at 18 weeks of age. This indicates the antibody might be more functional, and this was confirmed by the obsevation that the newborn group had lower nasopharyngeal carriage of vaccine type pneumococci and higher carriage of nonvaccine types at both 18 and 36 weeks of age.
PCV7 was well tolerated among both groups, with similar low rates of adverse events and severe adverse reactions reported in both groups. One nonvaccine-related death occurred in both groups.
“Functionally, despite the absence of demonstrable antibody responses in the first six weeks, when given at birth the vaccine clearly primed the infants in a way that they had more functional antibody that protect them from acquisition of pneumococci over the first 36 weeks of life. In resource-poor settings with high transmission of pneumococci, that could translate into clinical protection,” Goldblatt said. – by Nicole Blazek