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:
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.

Does white wine give you skin cancer?

Many studies have shown that drinking wine, especially red wine, seems to have modest benefits for heart health, as long as you drink it in moderate amounts. A study published this week, though, offers a more worrisome message: white wine might increase your risk of skin cancer.

The bottom line: a daily glass of white wine carries a 13% increased risk of melanoma, one of the deadliest forms of skin cancer. Surprisingly, though, red wine did not carry the same risk. In fact, when the authors separated out beer, red wine, white wine, and other forms of alcohol, only white wine carried any risk for melanoma. 

Should you cut back on white wine based on this new finding? I read the study to find out more.

The new study, led by Eunyoung Cho from Brown University, appeared in the most recent issue of a journal published by the American Association for Cancer Research. It's a large, carefully-done analysis of survey information from over 210,000 health professionals, about two-thirds of them nurses, followed over an 18-year period. The 210,000 participants came from 3 studies: 2 studies of nurses and one of male health professionals. About three-quarters of the participants were female, and the vast majority were white (which means the findings might not apply to non-white populations).

One feature I always look for in an analysis like this is a dose-response effect. If the effect is genuine, then higher doses (in this case, more alcohol) should increase the risk. The authors here found that people who drank the most alcohol had the greatest increase in risk. The study also controlled for all the usual confounding factors, such as family history of cancer and smoking. 

In some subgroups–those who drank the most white wine–the increased in relative risk of melanoma was 50% or more. Keep in mind, though, that this is "relative risk." I'll get to that in a minute.

When the researchers looked at where the cancer occurred, they found that the risk of melanoma was "far greater" on areas of the body that don't receive regular sun exposure, such as the stomach and back, compared to the arms or neck where people get the most sun. This result suggests that the effect of alcohol is unrelated to sun exposure.

There are several important caveats about this study. Perhaps the biggest is that the mechanism is unclear: how does white wine cause melanoma? The authors suggest that the effect is due to acetaldehyde, a cancer-causing compound that is present in wine. However, both red and white wine contain this compound, so it's not clear why white wine would carry a greater risk. It's also not clear why acetaldehyde should cause skin cancer more than other cancers, and why it should be associated with skin cancer specifically on areas of the body that are not exposed to the sun. 

Before you panic, let's revisit the actual amount of risk here. The 13% increase in risk does not mean that you have a 13% chance of getting melanoma from drinking white wine. I looked at the raw numbers in the study, and the overall rate of melanoma in non-drinkers (about 71,000 people in this study) was 0.61%. About 26,000 people reported drinking 10-20 grams of alcohol per day (the equivalent of 1 or more glasses of wine), but the study didn't report how many of these people drank white wine. Nonetheless, in this group the rate of melanoma was 0.85%. So in raw numbers, the increased risk for melanoma was 0.24%.

That's a rather small number, but it's still worrisome. The National Cancer Institute warns that alcohol is linked to several types of cancer (although not melanoma), especially for those who drink excessively. The new study reinforces that warning, and suggests that for those who drink wine, red wine might carry fewer risks than white.

I'm still a bit skeptical, because we have no good explanation for why white wine–but not red wine, beer, or alcohol–would cause skin cancer.  But still, when you reach for a glass of wine this holiday season, perhaps you should choose red instead of white.