Rising Mumps cases even in vaccinated populations in the United States over the past decade have raised doubts about mumps vaccine efficacy. Researchers examined these outbreaks using mumps vaccine effectiveness data.They found that the increase in mumps cases is more consistent with loss of vaccine protection over time, rather than incomplete protection against an evolving virus population or lack of immune response to the vaccine. Their work also suggested that a third vaccine dose may extend protection, which could prove useful in designing a clinical action plan to prevent the spread of mumps.
After decades of declining mumps incidence amid widespread vaccination, the United States and other developed countries have experienced a resurgence in mumps cases over the last decade. Outbreaks affecting vaccinated individuals and communities with high vaccine coverage have prompted concerns about the effectiveness of the vaccine currently in use. It is unclear whether immune protection wanes or whether the vaccine protects inadequately against currently circulating mumps virus. Routine use of a third vaccine dose at 18 years of age, or booster dosing throughout adulthood, ‘may be a strategy to prevent mumps re-emergence and should be assessed in clinical trials’ say the research authors.