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Mumps and Rubella: Stepchildren of the MMR?
The number of US cases of mumps in recent years may surprise you. What's behind the rise and why don't we hear about it?
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Question: How many cases of mumps were reported in 2016 by the CDC?
A. 223
B. 579
C. 1,088
D. 5,311
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The correct answer is: D. 5,311 (vs the 70 cases of measles)
At least 45 states reported cases, so the problem is widespread. At the end of February 2017, more than 1,000 cases had been reported, so the problem is getting worse. Before the vaccine against mumps was licensed in 1967, more than 180,000 cases per year was the norm. This raises another good question:
What is the effectiveness of the currently recommended 2 doses of mumps vaccine?
A. 70% (range 62%-79%)
B. 88% (range 65%- 95%)
C. 93% (range 78%-97%)
D. 97% (range 88%-99%)
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The correct answer is: B. 88% effective (vs 97% effectiveness for 2 doses of measles vaccine).
Most mumps outbreaks have occurred on college campuses which are great settings for contagious diseases: crowded conditions and lots of saliva swapping (sharing drinks, lipstick, cigarettes, not to mention the kissing, etc). Put one mumps-infected student in a bar with 100 vaccinated classmates and up to 12 others may become infected. Adults are not spared. Over 20 NHL players on five different teams were infected in a 2014 mumps outbreak.
Why more now?
What explains the surge in mumps cases? The circulating mumps strain is matched to the one in the current vaccine, so that is not the problem. Waning immunity most likely has a role. Secondary schools also crowd kids together, but college students are another 5-10 years removed from that second and last dose of MMR, usually given at age 4-5 years. Some experts are calling for a third booster dose.
It seems to me that measles outbreaks get wider press coverage than mumps outbreaks do. Yes, measles has a higher death and hospitalization rate, but mumps, like the measles, can cause an encephalitis that can lead to deafness and even death. Other mumps complication include orchitis, oophoritis (inflammation of the ovaries), and meningitis. Infertility is more of an urban myth; it rarely happens.
The MMR vaccine is often referred to as “the measles” vaccine. Mumps and rubella, both scary conditions in their own right, seem to be treated as mere afterthoughts to measles protection. Perhaps, like Cinderella, they are the belittled stepchildren when compared to the "real child," in this case, measles.
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