Contagion.

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How Hockey Got the Mumps

Cass R. Sunstein is a Bloomberg View columnist. He is the author of “The World According to Star Wars” and a co-author of “Nudge: Improving Decisions About Health, Wealth and Happiness.”
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Over the past two months, the National Hockey League has experienced a baffling outbreak of mumps. Thirteen players are said to have it, and there's no telling when the outbreak will end. It is a story that seems to have stepped from the mid-20th century.

Before 1967, about 180,000 Americans had mumps every year. Sometimes the number was well over 200,000. While the illness is only rarely fatal, it is worse than unpleasant, producing fever, headache, fatigue and loss of appetite.

By 2012, the number of reported cases shrunk to 229. Mumps has hardly been wiped out, but in terms of public health, the improvement has been nothing short of spectacular.

You may already have guessed the reason: comprehensive vaccination. In 1967, the first vaccine against mumps was licensed in the U.S., and 40 years later childhood inoculation helped reduce disease rates by an astonishing 99 percent. Today, the vaccine is included in two combination vaccines: measles-mumps-rubella and measles-mumps-rubella-varicella.

The success story is worth underlining because both Canada and the U.S. are now experiencing an anti-vaccination movement, limited to a small part of the population, but nonetheless worthy of concern. The movement is borne from the fear, unsupported by scientific evidence, that vaccines (including MMR) can cause autism.

That fear is itself dangerous, because it leads some parents to subject their children to serious risks by keeping them from getting their shots. In certain places, including in Canada, vaccination rates have dropped. And in the Western world, again including Canada, diseases that are preventable with vaccines -- not only mumps but also measles, chicken pox and whopping cough -- have been resurfacing. One reason appears to be the anti-vaccination movement. According to Dr. Gerald Evans, director of infection control at Canada’s Kingston General Hospital, recent outbreaks in Canada are “all because of vaccination rates falling. It’s 100 per cent blamed on the fact that people aren’t getting vaccinated.”

Evidence also suggests that current public health communications that attempt to address people’s concerns may actually be reinforcing them.

Which brings us back to the NHL. We cannot know for sure, but it is not unreasonable to speculate that the outbreak among hockey players may be related to lower vaccination rates in Canada, spurred by the anti-vaccination movement. At the very least, it's clear that those who do not vaccinate their children, or themselves, are endangering not only their own families but strangers as well.

To date, the NHL outbreak has not been stopped, notwithstanding widespread vaccinations among the players. For example, the Buffalo Sabres recently vaccinated all players.

One problem is that the vaccine is not completely effective. While it greatly reduces the risk -- one dose by 70 to 80 percent, two doses by 90 percent -- some vulnerability remains. Because hockey is a high-contact sport, exposure cannot easily be avoided.

In addition to getting vaccinated, it makes sense for players to have their own water bottles and to use hand sanitizers -- and for those whose glands start to swell (in the early stage of mumps) to stay home to avoid infecting others. If such steps are taken, there’s every reason to think that the outbreak will eventually be controlled.

Peter DeBoer, coach of the New Jersey Devils, had some wise words for hockey, for vaccination, and for life in general: "We've done all the precautionary things you can do, and other than that, you just cross your fingers and hope no one else gets it."

This column does not necessarily reflect the opinion of Bloomberg View's editorial board or Bloomberg LP, its owners and investors.

To contact the author on this story:
Cass R Sunstein at csunstein1@bloomberg.net

To contact the editor on this story:
Mary Duenwald at mduenwald@bloomberg.net