Mumps Fact Sheet

No.

It is safe to give a third dose of MMR vaccine if an individual cannot provide documentation of earlier doses.

In general, it takes 10-14 days to mount a response to a vaccine if it is the body's first exposure. Then it takes approximately seven days after the second exposure.

Mumps is spread by exposure to droplets from the nose or mouth, usually from a cough or sneeze, or by direct contact with saliva. Someone who is not wearing a mask and is within three feet of a case when the case is contagious would be considered exposed. There is not a specific length of time that a person needs to be in contact to be considered exposed. Mumps is about as contagious as influenza and rubella but less so than measles and chickenpox (varicella).

No. Children under 12 months will have immunity from their mothers, if they are immune. At this time, IDPH is not recommending giving the first or second dose early.

No. At this time, IDPH is not recommending giving the second dose early.

There have been many questions about why people who have been vaccinated are getting mumps. As you read through the examples that follow, keep these key points in mind.

• The mumps vaccine (part of the MMR vaccine) may be up to 95% effective.
• This means out of every 100 people vaccinated, 95 will be protected. However, the vaccine will not "take" in 5 people, and these people will remain susceptible to the disease.
• By comparison, the measles vaccine (also part of the MMR vaccine) is about 98% effective and the annual influenza vaccine is about 70-85% effective.

Example 1:

In a community of 100 people, 100% have been vaccinated. Everyone is exposed to mumps. What happens?

• 95 people (95%) in the community are protected by the vaccine and do not get mumps.
• 5 people (5%) in the community become ill with mumps because the vaccine did not "take".
• Of the 5 people who get mumps, all (100%) have been vaccinated.

Example 2:

In a community of 100, 98% have been vaccinated (a similar rate to what is being seen today in Iowa's K-12 schools and some colleges.) Thus 98 people are vaccinated and 2 people are not. Everyone is exposed to mumps. What happens?

• 93 people (95% of the 98 who are vaccinated) in the community are protected by the vaccine and do not get mumps.
• 5 people (5% of the 98 who are vaccinated) become ill with mumps because the vaccine did not "take".
• 2 people who have never been vaccinated get ill because they have no immunity to the disease.
• Of the 7 (5 vaccinated +2 unvaccinated) people who get mumps, 71% (5/7) were vaccinated. (This is similar to what is happening now in Iowa.)

Thus a large percent of the people with mumps have been vaccinated. This is expected in a highly vaccinated population when dealing with a vaccine that is up to 95% effective and a contagious disease like mumps. This does not mean that the vaccine is not working; in fact the mumps vaccine is working as expected.