Last updated on August 24th, 2019 at 12:20 pm
I get to do a click-bait article talking about Sidney Crosby, of the Pittsburgh Penguins, one of the most talented and exciting young ice hockey players in the National Hockey League (NHL), the top level of ice hockey in North America (if not the world). It’s a sport dominated by Canadians, Russians, Czechs, Finns, Swedes, and Americans, though there are a smattering of players from other countries especially in Central/Northern Europe. In Canada, hockey is a religion.
Sidney Crosby with the mumps. ©2014, NHL, Pittsburgh Penguins
And I love hockey. Yes, I know it’s a sport whose fans are located in freezing cold parts of the world, and has absolutely 0 interest outside of maybe 10 countries. But it’s a truly world sport, with players from all kinds of countries. I sat a game last year where a whole row of fans travelled from Finland to the USA to watch one player. They chatted with other fans, used iPhones (poor Nokia) to text photos to their friends back in Helsinki, and complained about US beers. You don’t get that at a American football or baseball game.
So, why are we talking about Sidney Crosby and ice hockey in a scientific skeptics blog? Well, it’s not really about click baiting (though I need to try that once), it’s because Crosby has come down with the mumps. Worse yet, the NHL appears to have a mini-outbreak of mumps with 13 players, two referees, and numerous coaches, staff, and other NHL team employees contracting the disease.
What is mumps? It is a virus that causes flu-like symptoms (it is not related) followed by swelling of the salivary glands, causing the swollen look of mumps victims. It’s a rather uncomplicated disease–until such point it causes serious, sometimes dangerous, complications. The most common complication is inflammation of the testicles (orchitis) in males who have reached puberty, which rarely causes fertility problems including sterility.
Mumps is very infectious, easily transmitted by saliva from person to person.
Other complications include encephalitis or meningitis which has an extraordinary risk of occurring in 15 out of 100 infected adults (pdf), inflammation of ovaries or breasts in females who have reached puberty, and pancreatitis which has a relatively high risk of occurring in 5 out of 100 infected adults (pdf). Deafness is a rare but statistically significant complication, appearing in 1 out of 20000 infected patients. Death is extremely rare for mumps, but when it does happen, it almost always happens to adults.
Today, with the success of the mumps vaccination, which is part of the MMR vaccine for mumps, measles and rubella, mumps is extraordinarily rare. In 1967, there were 186,000 cases of mumps in the United States–translating that to the current USA population, there would be approximately 280,000 annual cases. Canada, the other country where the NHL has teams, has had a similar 99% decrease in mumps cases since the release of the MMR vaccine.
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The mini-outbreak of mumps in the NHL really is not an indicator of anything including failure of vaccines. There are about 650 players in the NHL, and only 13 have caught it. Considering how close these players are to each other during and after games, or if there was some highly infectious mumps virus or no one was vaccinated, we wouldn’t be observing just 2% of the players coming down with the mumps. Maybe we’d see 100-300 players, but we don’t.
What do we know?
First, we will probably not be able to figure out who “patient zero” is. Mumps has a relatively long infectious stage of 2-3 weeks with the first part of that period the patient is asymptomatic, meaning that Sidney Crosby could have been spreading the virus for 20 days before actually exhibiting symptoms. Moreover, it’s possible that some or all of the NHL cases arose when players were in their home country, or at an international tournament–they all contracted it separately. So, we really don’t know how it started.
Second, specifically in Sidney Crosby’s case, he was immunized as a child, and received a booster recently, prior to attending the 2014 Olympics in Sochi, Russia. Some professional sports teams have stringent policies about vaccinating their coaches and players (but for unknown reasons, they do not have that same policy for staff, which could be a way the virus gets to the team). These multi-billion dollar enterprises do not want to risk losing games because a flu outbreak hits the team right before an important match, which makes me wonder why vaccinations aren’t more mandatory for players and all staff.
Third, and I hate having to make this clear for 47th time, but just because Crosby was vaccinated (and recently), and he contracted mumps, it does not mean the vaccine is a failure. Again, if it were a failure we’d be reading about 200 or 300 NHL players with the mumps (which would be a disaster for the league). And 13 players infected out of around 650 is such a tiny sampling in a tiny, highly biased population, almost hits the lowest level of statistical value we could find.
So what is happening? I suspect some sort of “vaccine failure”, which falls into a few broad groups:
- The patient’s immune system does not produce sufficient antibodies in response the vaccine. This could be as a result of the vaccine itself–the antigens present in the vaccine no longer confer resistance to the circulating pathogen, such as we are seeing with the current 2014 flu vaccine. Or, it could be some characteristic of the patient where no or inadequate numbers of antibodies are produced by the immune system. This isn’t precisely the fault of the vaccine, since immune responses vary from human to human based on dozens of factors.
- There might be another reason why effectiveness of the mumps component is lower than expected–waning immunity. Although the immune system remembers all antigens theoretically forever, in reality, without constant challenges, immunity could wane over time. With each breath, we inhale literally millions of antigens, so the database of antibodies within our immune system gets pretty crowded. It’s possible that the database can be unlimited, but we’re not sure. Waning immunity is an issue with several vaccines, including whooping cough.
- There is strong evidence that the recent increase in mumps outbreaks in the USA may be related to both a lower antibody level over time and incomplete vaccination (meaning getting only 1 of 2 doses). In addition, because of nearly non-existent exposure to the wild virus (thanks to the success of vaccinations), those who only had one dose never get a “natural” booster, and then are at risk to the disease, especially in a closed environment like a college, when someone brings the virus from another country where mumps has larger epidemics or is endemic, like the UK where a recent outbreak hit over 70,000 people.
The best data available says that the mumps vaccine component of MMR is extremely effective in preventing mumps. A recent Cochrane systematic review of the MMR vaccine concluded that the effectiveness of the mumps component of the vaccines was approximately 85-88% after two doses of the vaccine.
Setting aside antibodies and vaccines, the NHL needs to be taken to task on how it’s dealt with this mini-outbreak. After the first few cases, four players on the Anaheim Ducks along with five players on the Minnesota Wild, the NHL should have aggressively vaccinated all players, referees, and front office personnel against mumps. Some teams have, but it appears that the NHL has been rather lackadaisical in their response to protecting their multi-million dollar salaried players who are basis of winning or losing seasons. They seem to not realize that other personnel, not necessarily just on-ice players, coaches and refs, can transmit (or contract) the disease.
And what about the fans? We get pucks and sticks from the players, who hand them to us with gloves on which they’ve slobbered and spit. What about game worn equipment, which is more valuable if it’s not been washed? It carries the virus for some amount of time. What if a player sneezes his mumps virus (before he’s symptomatic) onto fans right behind the bench. Or even vice versa.
But all of that is the NHL’s problem, and they seem to be reacting at a glacial speed.
The point is, this mini-outbreak isn’t particularly worrisome, except Sidney Crosby is sick, so it gets our attention. But lots of kids are getting mumps because parents are refusing immunizations for them or because they can’t be vaccinated. Those kids should get our attention too. But I hope that Crosby gets better, has no complications, and scores a hat trick against the New York Rangers. That’ll work for me.
If you need to search for scientific information and evidence about vaccines try the Science-based Vaccine Search Engine.
Key citations:
- Dayan GH, Quinlisk MP, Parker AA, Barskey AE, Harris ML, Schwartz JM, Hunt K, Finley CG, Leschinsky DP, O’Keefe AL, Clayton J, Kightlinger LK, Dietle EG, Berg J, Kenyon CL, Goldstein ST, Stokley SK, Redd SB, Rota PA, Rota J, Bi D, Roush SW, Bridges CB, Santibanez TA, Parashar U, Bellini WJ, Seward JF. Recent resurgence of mumps in the United States. N Engl J Med. 2008 Apr 10;358(15):1580-9. doi: 10.1056/NEJMoa0706589. PubMed PMID: 18403766.
- Demicheli V, Rivetti A, Debalini MG, Di Pietrantonj C. Vaccines for measles, mumps and rubella in children. Cochrane Database Syst Rev. 2012 Feb 15;2:CD004407. doi: 10.1002/14651858.CD004407.pub3. Review. PubMed PMID: 22336803.
