Mumps outbreaks reflect weakened immunity.
Aweakening immune response to the virus that causes mumps, not mutated strains of the virus, is the explanation behind recent mumps outbreaks in vaccinated populations, according to a recent study.
The authors concluded that these outbreaks, which recently have affected mostly young adults, "reflect a Progressively weakening immune response to mumps viruses that occurs over the years following childhood vaccination," according to a summary of the study (J. Virol. 2011 Nov. 9 [doi:10.1128/JVI.06125-11]) posted on the Food and Drug Administration's website.
Several of the researchers, including lead author Steven A. Rubin, are from the division of viral products in FDA's Center for Biologies Evaluation and Research.
"The study opens the door to consider whether the most effective strategy - would be to revaccinate adolescents in order to restore their immunity to these viruses," not the development of a new vaccine against new strains of the mumps virus, the FDA statement said.
The study involved testing sera from children 6 weeks after they were given the measles, mumps, and rubella (MMR) vaccine and found that antibodies triggered by the vaccine neutralized a variety of strains of the virus, providing "strong evidence [that] mumps viruses were not changing so much that anti bodies triggered by the vaccine could no longer recognize them," according to the FDA statement. "Instead, the immune response triggered by the initial vaccination appears to weaken over the years in some people, but can likely be rejuvenated by revaccinating ... adolescents."