We are now seeing the largest mumps outbreak in the U.S. in the past 20 years. As of May 2, there were 2,597 reported cases, with the largest number in Iowa, where the outbreak began on a college campus. The rest of the cases are in the surrounding Midwestern states. The outbreak has not reached North Carolina yet, but in a mobile community where people do travel, it certainly could.
Mumps is a viral disease caused by the mumps virus; symptoms include flu-like symptoms (fever, tiredness) and the characteristic swelling of the salivary glands. It is generally uncomfortable but not medically serious.
However, rare complications include encephalitis, meningitis, orchitis, early spontaneous abortion but these are very rare. In the current outbreak, only about 20 people have had to be hospitalized.
There is public concern about the MMR (measles-mumps-rubella) vaccine because people are hearing that many of the sick individuals were vaccinated.
Here’s the situation the vaccine is a very good vaccine, but like any vaccine, it is not perfect. We know that it “takes” about 80% of the time in people who get one dose and about 90% of the time when two doses are given.
Mumps used to be a very common disease in childhood but it is now very rare thanks to the vaccine. If the vaccine wasn't as good as it is, we wouldn’t be so shocked by this outbreak! Without the vaccine, a lot more people would be ill right now.
The current outbreak began and centered on a college campus where students live in very close quarters, eat together, attend sporting events together, etc. Environments like that are always good places for infections to take hold and spread.
A lot of people want to know about the vaccination status of the cases; among the 1192 patients in Iowa, six percent were unvaccinated, 12% had one dose, 51% had two doses of MMR and 31% were unknown. This does not mean that the vaccine was ineffective — the MMR is a very good vaccine, with good coverage — but as with any vaccine, it is not 100% effective.
Lower vaccination rates would have meant much higher incidence of disease than we have seen in this outbreak. Of interest to North Carolina – it is one of a number of states that require two doses of MMR documented to enter college, in order to reduce the likelihood of outbreaks like this beginning or spreading on college campuses, where close living quarters make for “good” places for infectious diseases to spread.
Make sure you are vaccinated. Most primary care doctors offices have the MMR vaccine on hand. The CDC is currently working in the affected states to help make sure that there is good vaccine coverage, and the MMR manufacturer, Merck, has donated 25,000 extra doses of the vaccine to CDC. The vaccine is recommended just after a child’s first birthday and then the second dose between ages four and six-years-old. It has NOT been studied in young infants so should not be given before the first birthday. For the elderly, birth before 1957 is generally considered proof of immunity since most people in that era contracted mumps as a childhood disease.
Wash your hands frequently and well with soap and water. If you are sick, limiting contact with others to whom you might spread the disease is a good idea. The CDC recommends that anyone with mumps should stay away from school or work for nine days.
In addition to the basic take home message about how to protect yourself, this outbreak is a really interesting study in vaccine effectiveness, and the importance of understanding what the benefits and weaknesses of any vaccine and vaccine sequence are.
There have been rumors that this outbreak is related to waning protection, but to date the CDC has not found that to be the case. For many vaccines, however, it is true that we don’t know exactly how long they are protective and when or if a booster is needed. Those studies take many years, and we wouldn’t want to delay implementing good vaccines to do them, but we need to make sure they are being done once the vaccine is introduced. As we continue to increase the number of recommended vaccines, and to add the adolescent vaccines that are coming down the pipeline, getting a handle on these issues is going to be critical. The vaccine schedule is becoming long and complicated — and will get even more so in the coming years.