Despite routine use of a childhood vaccine, the United States still sees outbreaks of mumps. Now, a new study reinforces the belief that it's due to waning immunity post-vaccination.

Mumps is a viral infection best known for causing puffy cheeks, a swollen jaw, fever and general misery. While it's usually relatively mild, mumps occasionally causes serious complications like brain inflamma...

Children and teenagers vaccinated against the mumps virus have accounted for one-third of infections in recent years, a new U.S. government study finds.

The reasons are unclear, and experts stressed that routine childhood vaccination remains the best weapon against mumps -- a contagious infection that is usually mild, but can cause serious complications.

After the mumps vaccine was ...