Could my son get the mumps even if he’s had the MMR vaccine?

DEAR DOCTOR K:

A few students at my son’s college have been diagnosed with mumps. My son has had all of his vaccines, including the MMR. Could he still get mumps?

DEAR READER:

Mumps is an infection that causes swelling of the parotid glands in front of each ear. It is caused by a virus that spreads from person to person through coughs, sneezes and saliva. It can also spread through contact with contaminated items and surfaces. Once the mumps virus enters the body, it passes into the bloodstream and can spread to many different glands, as well as the brain.

People with mumps are contagious during a period that begins 48 hours before and ends six to nine days after the beginning of symptoms.

Thanks to the mumps vaccine, which was introduced in the 1960s, the number of annual cases has decreased by more than 99 percent. The measles-mumps-rubella (MMR) vaccine is given in two doses. The first dose is given at 12 through 15 months of age. The second dose is given at 4 through 6 years of age.

The vaccine prevents most, but not all, cases of mumps and complications caused by the disease. People who have received two doses of the MMR vaccine are about nine times less likely to get mumps than unvaccinated people. However, some people who received two doses of MMR can still get mumps, especially if they have prolonged close contact with someone who has the disease. Still, a vaccinated person who gets mumps will likely have less severe illness than an unvaccinated person.

In about 15 to 20 percent of patients, mumps does not cause any symptoms. When symptoms occur, they usually begin 14 to 18 days after exposure to someone with a mumps infection.

Symptoms of mumps infection may include fever, headache, sore throat, muscle aches, poor appetite and malaise (a general feeling of sickness). As I mentioned, the mumps virus causes pain and swelling of the parotid glands in front of the earlobes; the swelling is called parotitis. This can make chewing and swallowing very uncomfortable.

Mumps parotitis can occur very rapidly. I know, and not just because I’m a doctor, but because I’ve had it. One afternoon I felt lousy: my muscles ached, my energy was poor and I didn’t feel much like dinner. I went to bed early. Sometime in the middle of the night I woke up because it felt like my face was resting on a walnut someone had placed on the mattress. The “walnut” was my parotid gland. Fortunately, I recovered without more serious complications.

By getting the mumps vaccine, your son has greatly reduced his risk of ever getting the mumps. The vaccine is not perfect, and so his risk is not zero. But you can tell him from me: Be grateful there’s a vaccine. The virus got me before there was a vaccine — and it was no fun.