U.K. mumps outbreak linked to waning MMR protection

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The recent measles outbreak in Wales reconfirmed the effectiveness of one component of the measles, mumps and rubella (MMR) vaccine. Immunization with MMR is an almost surefire way to protect against measles. Its effectiveness in protecting against mumps is less clear though.  

A growing body of evidence suggests MMR offers lower levels of protection against mumps than measles and rubella from the start, and then gradually declines. The recent surge in the number of mumps cases in the United Kingdom has added weight to this theory. After finding that half of recent mumps cases involved people who had received at least one dose of MMR, Public Health England (PHE) reported "some waning immunity may be contributing to transmission." PHE is convinced enough by the data to call on the National Health Service (NHS)--which sources MMR vaccines from GlaxoSmithKline ($GSK) and Sanofi ($SNY)--to change its advice.  

PHE is specifically targeting an NHS question and answer document about MMR, The Guardian reports. The current Q&A says MMR "probably" offers lifelong immunity, and mumps outbreaks still happen because in the past some people only received one dose. PHE believes the wording needs changing to reflect doubts about the long-term immunity MMR offers against mumps. Its version would state protection against mumps is lower than measles and rubella after two doses--90-95% compared to 99%--and appears to gradually decline. While unvaccinated people are at the most risk, even those who receive two jabs "can catch mumps and pass the infection on to their close contacts without even knowing it," the PHE draft reads.

If true, this finding reinforces the need to vaccinate. "[It] makes it even more important for the unvaccinated to have the vaccine because herd immunity is not high, so individual protection relies on your own vaccination," PHE immunization head Mary Ramsay said.

- read The Guardian's take

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