Four-year results assessing the efficacy of the United Kingdom (UK) meningitis C vaccine program are reported in a research letter in this weeks issue of The Lancet. The vaccine is now showing long-term efficacy, except for infants initially vaccinated younger than five months of age.
The meningococcal serogroup C conjugate (MCC) vaccine program was introduced in November 1999 and has successfully controlled the incidence of meningitis Ca result of high short-term vaccine effectiveness and substantial herd (population) immunity. However, the long-term effectiveness of the vaccine remains unknown.
Caroline Trotter (UK Health Protection Agency) and colleagues assessed surveillance data from the four years since the introduction of the vaccination program. Vaccine effectiveness remained high in children vaccinated in the catch-up campaign (age five months to 18 years) at around 90 percent. However, overall vaccine effectiveness was only 66 percent for children vaccinated in early infancy. The vaccine offered high levels of protection (greater than 93 percent effectiveness) for one year, regardless of the age of the child at vaccination; however this protection rapidly diminished for children who were vaccinated in early infancy (younger than five months of age). With regard to this reduced protection, the authors comment: The number of cases of serogroup C disease in these cohorts remains low, but alternative routine immunization schedules should be considered to ensure high levels of protection are sustained.
Paul A. Offit (University of Pennsylvania School of Medicine,
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Dr. Paul A. Offit, Childrens Hospital of Philadelphia,
Source: The Lancet