FROM THE CMAJ

A study that followed up children aged 5 years who had received a meningococcal group B vaccine as infants in an earlier study determined that protective antibody levels against the strains covered by the vaccine dropped over time, with variations depending on the strains and vaccine dose schedules, the investigators reported.

The phase II, open-label study evaluated serum levels of protective antibodies to the strains included in the serogroup B meningococcal vaccine manufactured by Novartis in 50 infants, 18-20 months after they had received the last dose. The results “provide important new information about how the persistence, at 5 years of age, of bactericidal activity induced by administration of 4CMenB vaccine differs between test strains and with different vaccination schedules,” wrote Dr. Fiona McQuaid of the Oxford Vaccine Group, Oxford University, and her coauthors. The study was published online March 23 in the CMAJ (2015 [doi:10.1503/cmaj.141200]).

The authors pointed out that there are limited data on the persistence of antibody responses after toddler and infant immunization and after booster doses, but this information “will be important for guiding the implementation” by the United Kingdom Joint Committee on Vaccination and Immunization recommendation that the 4CMenB vaccine be included in the routine U.K. immunization schedule.

Among the 16 children who had received the vaccine at 2, 4, 6, 12, and 40 months, 44%-88% had antibodies against strains in the vaccine that were protective, which varied by strains, at age 5 years. Among the five children who received the vaccine at 12, 40, and 42 months, 80%-100% had protective antibodies against vaccine strains. Among the 29 children who had received the vaccine at 40 and 42 months, 31%-100% had protective antibodies against vaccine strains. “Waning of antibody titres was observed for those immunized as infants, but the extent of waning varied by strain,” the authors observed.

The most common adverse events after the first and second doses were injection site pain and erythema; the rate of fever was low.

Although the study had limitations, including the small sample size, the data “give an early indication that protection against serogroup B meningococcal disease after infant immunization is unlikely to persist into adolescence, when the second peak of incidence occurs,” the authors wrote.

“The steep decline in disease incidence after the first year of life means that schedules involving vaccination at 40 and 42 months and at 60 and 62 months may not have a substantial effect on the number of cases and are therefore less likely to be used if the incidence of disease remains at its current low levels,” they noted, but added that their data “will prove useful in planning for a future epidemic or for countries planning catch-up campaigns.”

The Novartis vaccine (Bexsero) and Pfizer’s meningococcal group B vaccine, Trumenba, which are approved in Europe and other countries, were recently approved in the United States. At a meeting in February, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices recommended serogroup B meningococcal vaccination for several groups at increased risk for serogroup B disease, including students during outbreaks at college campuses. Broader use of these vaccines in adolescents and college students is on the agenda of the next ACIP meeting in June 2015.

Dr. McQuaid and her coauthors pointed out that, in Canada, meningococcal B vaccination is recommended for those in high-risk groups, and that introducing the vaccine as a routine vaccine in the United Kingdom “provides an ideal opportunity to assess the effect of this vaccine in a real-world setting and will guide the implementation of 4CMenB vaccination in Canada and worldwide.”

In an interview, Dr. McQuaid noted that the vaccine is licensed for use in the United States for people aged 10-25 years, while this study focused on children immunized as infants and at 5 years of age and does not necessarily apply to older age groups.

In Europe, the vaccine is licensed from 2 months of age, “and these data show that children immunized at 5 years of age have a good immunological response 1 month after two doses of the vaccine, which is important in the context of use during outbreaks.”

“The reactogenicity data will also help physicians inform parents of what to expect after vaccination,” she said, adding that, if the vaccine is introduced routinely into the United Kingdom, as recommended by the U.K. Joint Committee on Vaccination and Immunization,” this will provide a great deal of important information on how the vaccine works in a real-world setting.”

emechcatie@frontlinemedcom.com

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