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Revaccination May Result in Reduced Antibody Response

According to a study from England, repeated immunization using meningococcal polysaccharide vaccines may actually reduce antibody response.

"Widespread use of meningococcal A and C polysaccharide (MACP) vaccines has raised concerns about induction of hyporesponsiveness to these polysaccharides," wrote R. Borrow and colleagues, Withington Hospital, in the journal Vaccine. "Immunological hyporesponsiveness to C polysaccharide has been clearly documented in infants, children, and adults but only limited data from Gambian children are available for A polysaccharide."

"We investigated whether a second dose of MACP, given six months after an initial dose affected the immunological response as measured by the serum bactericidal assay (SBA) and enzyme-linked immunosorbent assay (ELISA), to serogroup A meningococci in young adults (university students, n=36)," the authors said ("Reduced antibody response to revaccination with meningococcal serogroup A polysaccharide vaccine in adults," Vaccine, 2000;19(9-10):1129-1132).

They evaluated serogroup A SEA responses one month following the second dose of MACP (geometric mean titre (GMT) 103.6, 95% CI 45.6-235.1). Borrow et al. found that immune responses were approximately one third of the levels observed one month after the first dose was administered (GMT 281.9, 95% CI 134.9-581.4).

The researchers also observed that the serogroup A-specific immunoglobulin G (IgG) levels after the second dose (GMC 21.2, 95% CI 15.3-29.4) were significantly lower. These IgG levels were on average three-quarters the level after the first dose (GMC 28.7, 95% CI 20.8-39.7).

"This confirms that revaccination with MACP vaccine, six months following the initial dose, results in a reduced immunological response to A polysaccharide in adults," concluded Borrow et al. "Repeated vaccination with MACP vaccine may be ineffective.

ALL INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR LEGAL ADVICE.  THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.