The Rest of the MMR: Mumps and Rubella

Given the content of the news over the past few weeks, I’m assuming you’ve heard about measles. If you haven’t, you need to check your internet connection—or maybe your pulse. But what about the rest of the MMR vaccine? What the heck are mumps and rubella, and why do we care?

Mumps

Like the other two diseases covered by the MMR vaccine, mumps is an illness caused by a virus. In many cases–maybe up to 50%, the symptoms are very mild and may be completely overlooked. Those people that do get symptoms typically have pretty non-specific complaints like fever, headache, fatigue, and muscle aches…until the cheeks swell up because of inflamed salivary glands and give away the diagnosis.

But it’s not just about puffy cheeks. Mumps can have some more serious complications as well. The most common is inflammation of the testicles (or, “orchitis”). This usually happens in post-pubescent males, and can–on rare occasions–cause infertility. Even when the function is retained, these vital organs can remain tender for weeks. Less commonly, the virus can cause inflammation of the breasts or ovaries, deafness (about 1/20,000), or inflammation in the brain. Adults infected with the virus have more severe symptoms including meningitis in about 15% of cases and pancreatitis in 5%.

In the 1960’s and early 1970’s, there were about 75,000 to 150,000 cases of mumps per year. The death rate from mumps hovers around 2 in 10,000—far better than measles, which is about 5-10 times that. The 2 recommended doses of the MMR vaccine are about 88% effective in preventing this disease. On a population level, rates of mumps virus infections have decreased by 99% since the vaccine was released in 1967. Of the three components of the MMR vaccine, the mumps protection is the weakest. There are still periodic mumps outbreaks that tend to cluster around college campuses or other communities living in close quarters—most famously in recent months, professional hockey players. Because immunity can fade over time, booster immunizations are recommended for adults in high-risk situations.

 

Rubella

This one is a little less straightforward. Rubella is also known as “German measles” or “three-day measles.” While the names can be confusing, rubella is caused by a totally different virus. The nicknames came about because the rash caused by the rubella virus looks similar to the measles rash, but the symptoms are far less severe and prolonged than measles.

About half of people infected with the rubella virus never notice it—no symptoms whatsoever. Those that do have symptoms may have a rash (similar to the measles rash), runny nose or congestion, mild fever, and maybe some achy joints. Two or three days later, they’re back to normal.

Seriously…getting rubella isn’t all that bad. So why do we bother to immunize against it?

We do it for the babies. While rubella may not seem laughable to those that get it, it can cause disastrous complications for a developing fetus if a pregnant women is infected. These complications occur in about 25-50% of babies born to mothers who are infected with rubella early in pregnancy (percentage goes up earlier in pregnancy). Congenital rubella syndrome is a bad deal and can cause intellectual disability, heart defects, deafness, and eye problems like retinopathy or cataracts, among other bad outcomes.

Women who have been immunized against rubella (or who have been previously infected by the rubella virus) are at much lower risk of having a baby with these problems. Testing for rubella immunity is a routine part of a woman’s prenatal care. If a pregnant woman is found to be non-immune to rubella, she can’t receive the MMR vaccine during pregnancy, so she would need to take special precautions to avoid exposure to the virus.

You may wonder why we bother immunizing boys against this illness, or why we don’t wait until later in life. Well, immunizations aren’t perfect. Because some women may be unable to form antibodies to this virus, herd immunity limits their chances of getting the virus by dramatically reducing how much the virus circulates. A pregnant woman without rubella immunity is at much lower risk of delivering a baby with congenital rubella syndrome if she’s not in contact with other individuals infected with the virus.


Immunizations are not a totally individual choice. They are designed not only to reduce a person’s own chances of acquiring an infection, but also to protect the public as a whole. We’ve seen the results of this recently with increases in cases of measles and pertussis (almost always in communities with low immunization rates). A parent’s decision not to immunize his or her children places other individuals at risk–whether they have a chronic disease that affects their immune function, are too young to be immunized, or simply can’t make antibodies to a specific virus.

Similar to speed limits and stop signs, immunization programs are a societal issue. They have been established to improve the health not only of individuals, but of our society as a whole. And, like speed limits and stop signs, immunizations are most effective when everybody participates. Just as the choice to drive recklessly has the potential to harm not only the driver, but also those around him, the decision to decline immunizations can affect others as well.