The MMR in the name "MMR vaccine" isn't just a long way of saying mister vaccine. According to the Houston Health Department, the mumps virus has infected at least seven people at a U.S. Immigration and Customs Enforcement (ICE) facility in Houston. Again, such serious complications of the mumps are very rare (less than 1% of all mumps cases) but are possible. One dose of the mumps vaccine is on average 78% effective at preventing mumps infections. The effectiveness of the mumps vaccine also depends on other people around you getting the vaccine.

Source: Forbes February 10, 2019 19:03 UTC