Health & Fitness

Do you need a third mumps vaccine? Experts stuck on an answer

Think you’re safe from mumps because you had your two vaccinations back when you were a kid?

Recent outbreaks — 360 students at the University of Missouri in Columbia battled the mumps this school year — have researchers thinking that two Measles-Mumps-Rubella vaccines might not be enough.

In what’s sure to disappoint needle-shy kids, they’re studying whether to add a third shot to the childhood vaccine regimen. They even are considering recommending a third shot for young adults in outbreak zones.

Every one of the infected MU students had been vaccinated as a child. But to try to stop the outbreak, MU told students that over the winter break they should get the third dose, which costs $100.

Nick Kelly, a freshman from Minnesota, said that caused a stir in his hometown doctor’s office.

“There was a lot of confusion and uncertainty as to why I was back for a third,” Kelly said. “They thought I’d be fine. I said, ‘Well, Mizzou suggested I get a third, and I’d like to not get the mumps, so that’s why I’m here.’ 

Why the confusion? Well, even some of the nation’s top infectious disease experts aren’t sure that a third dose of MMR does any good.

“There’s no harm in getting a third dose,” said William Atkinson, a retired Centers for Disease Control and Prevention epidemiologist. “It’s just that we’re not completely certain that strategy is useful.”

The CDC’s Advisory Committee on Immunization Practices has formed a work group to find out.

Atkinson, who has been part of other committee work groups, said the work group will be especially interested in outbreak zones like MU.

“There’s going to be a lot more discussion of this going forward,” said Atkinson, who now works for the Immunization Action Coalition, a Minnesota-based nonprofit that advocates for higher vaccination rates. “CDC has been intensely interested in this for the last decade.”

The CDC’s current recommendations call for two doses of MMR: one at 12 to 15 months of age and a booster between ages 4 and 6.

CDC recommendations generally determine what vaccines are covered by insurance and the vaccine schedule most doctors follow.

Before the vaccine went into wide use in 1967, hundreds of thousands of Americans got mumps every year, and in rare cases it caused serious or even fatal complications.

The initial vaccine was about 78 percent effective, and the booster dose, first recommended in 1998, raised that to 88 percent.

Because most of the population is vaccinated, most people who get the mumps now have had the vaccine. At the February meeting when the Advisory Committee on Immunization Practices formed the work group, a researcher said that’s causing a loss of confidence in the shot.

The outbreak at the University of Missouri and mini-outbreaks in Kansas contributed to 5,311 cases reported to the CDC in 2016. That’s the most the country has seen since 2006.

Mary Anne Jackson, an infectious disease expert at Children’s Mercy Hospital, said the decision to recommend a third shot will hinge on whether its effectiveness outweighs the cost of mass vaccination at $100 per shot and the possible side effects.

Jackson said the MMR shot is safe, but it sometimes causes joint pain when given to women after puberty.

“I think there’s a lot of things that need to be considered,” Jackson said, “and I think that’s why you don’t see the CDC moving very quickly on this.”

Missouri’s third dose experiment

The mumps outbreak in Columbia started with just a few students getting sick in September.

But it ballooned in late October and throughout November. Those first few cases became dozens, then hundreds, on the way to at least 365 confirmed cases.

Every student who came down with the illness had been vaccinated with two doses of MMR. As winter and peak mumps season approached, MU officials began mulling a third dose.

Susan Even, the director of the university’s student health center, said it was not an easy decision. Ramping up a mass vaccination campaign on a campus of 33,000 students takes time and money, and the CDC wasn’t much help.

The agency offers guidelines for considering a third dose, based on the length and intensity of outbreaks in confined areas like universities. Missouri fit the bill, but it still wasn’t a slam-dunk.

“They don’t call it a recommendation, they just say when these situations are present, consider whether offering a third MMR can be done,” said Even, who is the American College Health Association’s representative on the Advisory Committee on Immunization Practices panel.

The University of Illinois recommended a third dose to try to quell a mumps outbreak in 2015.

Illinois saw a decline in cases after that, but researchers who studied the outbreak said they couldn’t determine whether it was because of the third dose or just the normal course of the disease.

Even and the MU administration ultimately decided to ask students to get a third MMR dose when they went home after the semester ended Dec. 16.

The winter break then gave them time to get an on-campus vaccination clinic established by the time students returned. As of March 15, more than 4,000 students had been confirmed as having a third dose.

The mumps outbreak in Columbia seems to be dissipating. But just like at Illinois, Even said it’s difficult to pinpoint the cause. It’s still early in the vaccination campaign, and the university doesn’t know exactly how many students got a third dose at home.

Meanwhile, the mumps have spread to other Missouri campuses, and the Missouri Department of Health and Senior Services has issued its own recommendation that students at universities experiencing outbreaks should get a third dose

Kansas not recommending third dose

Mumps cases are also on the rise in Kansas, but there’s been no concentrated outbreak epicenter to spur consideration of a third dose.

The state’s 97 Kansas cases since December have been spread across 20 counties. Douglas County has had the most, with 16. Johnson County has had nine, and Wyandotte County has had one.

Of the 97 cases, 59 have had two documented doses of the MMR vaccine, and four have had one. Six are known to be unvaccinated, while the rest are unknown.

Charlie Hunt, the state epidemiologist, said there are no plans to recommend a third dose. But he said Kansas follows the CDC recommendations pretty closely.

“First, those who are not vaccinated, they should get vaccinated,” Hunt said. “Other than that, just be aware of the symptoms, stay home if they feel sick, cover their coughs and wash their hands.”

Hunt also said it’s important to keep the current outbreaks in context. There are still far fewer cases of mumps than there were pre-vaccine, and those that are occurring aren’t resulting in serious complications nearly as often.

In the pre-vaccine era mumps led to orchitis, a painful testicular inflammation that occasionally causes infertility, in more than 10 percent of males. It more rarely led to potentially fatal illnesses like meningitis, encephalitis and pancreatitis.

Hunt said those complications are hardly ever seen these days. He only knows of one mumps-related hospitalization in the current Kansas outbreak.

At MU, with more than three times the mumps cases, Even said she had also heard of only one hospitalization, which was for testicular pain.

Jackson said that’s consistent with outbreaks in other parts of the country: Even in areas where the mumps is spreading, it’s not as severe as it was before the vaccine.

“It appears to be strikingly more mild than it used to be,” Jackson said.

Andy Marso: 816-234-4055, @andymarso