The U.S. Is Officially Free of Measles—for Now

The MMR vaccine.
Photo: Getty Images

It looks like we can breathe a sigh of relief. Despite two new cases of measles being reported late last week in New York, federal and state health officials are confident the country’s measles-free status will stay in place. But the new cases highlight just how much a challenge lies ahead in controlling the spread of a disease that shouldn’t be here any longer.

Reuters reported Monday that the Centers for Disease Control and Prevention had documented two new cases of the viral disease last week. Initially, there was little other information about the cases, including whether they were connected to an outbreak in Rockland County, New York that had been raging since October 1 of last year. That’s a crucial detail, since a country’s measles-free status (dictated by the World Health Organization) can be revoked if the same strain of measles brought from another country circulates in a population for at least 12 months. Last Wednesday, Rockland County officials declared their outbreak over, following a 42-day period of no cases since August 13.

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As it turned out, these new cases were found in Rockland County. But importantly, officials said that the first case involved an international traveler from Israel, who then infected another person. In other words, this is thought to be a different chain of transmission, wholly unrelated to the earlier outbreak.

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State health officials had also been keeping an eye on two counties near Rockland, both of which had documented cases later than August 13. But on Thursday, the New York State Department of Health declared that these clusters of measles had ended as well. And with that, the measles outbreak in New York that began in October 2018 seems to have come to an end, just in the nick of time. The federal government’s Health and Human Services released its own statement Friday, confirming the news.

“We are very pleased that the measles outbreak has ended in New York and that measles is still considered eliminated in the United States,” said HHS Secretary Alex Azar.

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Still, given the new outbreak and total toll that measles had wrought on the U.S this year, it’s something of a pyrrhic victory. Also on Friday, research published by the CDC laid out the devastation in full.

From January 1, 2019 to this Tuesday, October 1, there have been 1,249 confirmed cases of measles reported, the highest yearly amount since 1992. And while measles is typically a flu-like illness for many sufferers, 10 percent of people sickened this year ended up hospitalized, and one developed a serious brain infection called encephalitis. Financially, it’s taken millions to control these outbreaks from spilling out further, including massive vaccination campaigns.

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People who receive the full two-dose measles, mumps, and rubella (MMR) vaccine are 99 percent less likely to contract measles. So understandably, 89 percent of reported cases were either unvaccinated or had an unknown immunization status. Since the median age of patients was 6 years old, though, the vast majority of victims were obviously kept from being vaccinated by their parents. Another 13 percent were infants, meaning they likely never had the chance to get vaccinated (the first shot is usually given at 12 to 15 months). That fact also highlights why herd immunity in a community is so important, since infants and others unable to get vaccinated can still be protected from measles if nearly everyone else (90 to 95 percent at minimum) is protected.

The overall measles vaccination rate is high and hasn’t fluctuated much in recent years, but there are many places of the country where rates are far below the herd immunity threshold. And in many of the areas where cases have struck this year, including New York, an unwarranted undercurrent of fear and suspicion toward vaccines, stoked by the anti-vax movement, has been festering for years.

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In Europe, the disease has surged back with a vengeance since 2017, with four countries including the UK losing their measles-free status this year. The U.S. has avoided that fate for now, and there have been new laws passed in states including New York and Maine that should increase vaccination rates by banning non-medical exemptions for childhood vaccine requirements to attend school. But so long as measles exists somewhere in the world, the threat of it returning as an endemic disease is always there. And we might not be so lucky next time.

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About the author

Ed Cara

Science writer at Gizmodo and pug aficionado elsewhere