Anti-vax movement helps create worst year of mumps in a decade

The year isn't quite over yet, but we've already had 4,258 cases of mumps in the U.S., more than any year since 2006, when we also experienced a dramatic spike in cases. As the chart here shows, before 2006 we only saw a couple of hundred cases per year, but the numbers have been trending higher since then. After two years with about 1200 cases each, this year looks to quadruple last year's total when the final numbers come in.

Source: CDC, Morbidity and Mortality Weekly Report (MMWR), Notifiable Diseases and Mortality Tables

Just as in 2005, the outbreaks were centered in a few states, mostly on college campuses in the middle of the country, especially Iowa, Illinois, and Indiana. (The 6500+ cases in 2005 were mostly in or near Iowa and Illinois.)

Why are we seeing this increase?

At least some of the blame, if not all of it, belongs to the anti-vaccine movement. Despite overwhelming evidence that vaccines save lives, and that the risks are miniscule compared to the enormous benefits, the anti-vaxxers remain in denial. They claim that the government–usually the CDC–and pharmaceutical companies have been conspiring for years to hide the so-called harms of vaccines, and they spread misinformation and fear in a continual effort to get parents to withhold vaccines from their children.

The main harm claimed by the anti-vax movement is autism. This belief, though fervently held by many anti-vaxxers, is absolutely false. It was originally proposed in a now-retracted, discredited 1998 study by Andrew Wakefield, who was later shown to have fraudently manipulated data, hidden his secret payments from lawyers who wanted to sue vaccine makers, and treated the children in his own study unethically. In 2010, Wakefield was stripped of his UK medical license. As the BMJ editors wrote in a 2011 editorial:

"Who perpetrated this fraud? There is no doubt that it was Wakefield."

Nonetheless, Wakefield he continues to promote his bogus claims (most recently with an anti-vax movie, which I won't name here to avoid promoting it), and remains a hero to the anti-vax movement, who seem blind to his flaws.

This is reprehensible–and frightening. If all parents followed the anti-vaxxers advice, we would see massive surges in vaccine-preventable illnesses, sometimes leading to permanent harm or even death in helpless children. Fortunately, most children are still getting their vaccines, but the anti-vaxxers have succeeded in reducing vaccination rates in many communities around the country, illustrated most recently by the 19-fold increase in vaccine exemptions in Texas.

Twenty years ago, we had under 200 cases of mumps per year, and it was no longer endemic in the United States. In other words, the only cases in the country were imported by people traveling here from other counties. The same was true for measles, which is much deadlier than mumps. Fortunately, rates of measles are low again this year, after the major outbreak that started in Disneyland in 2015, but if anti-vaxxers have their way, more outbreaks are in our future.

This amazing progress was all thanks to the mumps vaccine, which today is part of the MMR vaccine, which also protects you from measles and rubella. Before the vaccine program started in 1967, we saw about 186,000 cases of mumps annually in the U.S. The vaccine led to a 99% reduction in mumps (and measles). It's not perfect: the mumps vaccine is about 88% effective, but when everyone is vaccinated, "herd immunity" prevents the disease from spreading, even if a few people get sick. As the CDC explains,

"outbreaks are much larger in areas where vaccine coverage rates are lower."

Perhaps more alarming than the surge in mumps cases is that the U.S. has just elected the first anti-vaccine President in history. Others have documented Trump's "long, sordid antivaccine history," so I won't attempt to describe it here. We can only hope that reason will eventually prevail, and Trump's ignorance about vaccines won't lead to thousands of unnecessary cases of measles, mumps, whooping cough, and other diseases that vaccines can prevent.