Polimath has a good post on measles. The recent spike in U.S. cases has drawn alarm. As the New York Times reports:
There have now been more measles cases in 2025 than in any other year since the contagious virus was declared eliminated in the United States in 2000, according to new data released Wednesday by the Centers for Disease Control and Prevention.
The grim milestone represents an alarming setback for the country’s public health and heightens concerns that if childhood vaccination rates do not improve, deadly outbreaks of measles — once considered a disease of the past — will become the new normal.
But as Polimath notes, U.S. vaccination rates remain above 90% nationally. The problem isn’t broad domestic anti-vax sentiment but rather concentrated gaps in coverage, often within insular religious communities. These local shortfalls do explain how outbreaks spread once they begin—but how do they begin in the first place, given these communities are islands within a largely vaccinated country? Polimath says blame Canada! (and Mexico!)
The greater concern in my mind is not the problem of low measles vaccination coverage in the United States, but among our immediate neighbors. In Ontario, the MMR vaccination rate among 7-year-olds is under 70%. As in the examples above, this rate seems to be particularly low “in specific communities”, whatever that is supposed to mean. This has resulted in the ongoing spread of measles such that Ontario’s measles infection rate is 40 times higher than the United States. Canada officially “eliminated” measles in 1998. But with vaccine rates as low as they are, it seems like Canada is at risk for losing that “elimination” status and becoming an international source for measles.
Similarly, Mexico is having a measles outbreak that is substantially worse than the US outbreak. Importantly, the Mexican outbreak has been the worst in the Chihuahua province (over 3,000 cases), which borders Texas and New Mexico.
I’m less interested in blame than in the useful reminder that not all politics is American politics. Vaccination rates have dipped worldwide and not in response to U.S. politics or RFK Jr. In fact, despite RFK Jr. the U.S. is doing better than some of its North American and European peers. Outbreaks here may be triggered by cross-border exposure, not failures in U.S. public health alone. Not all politics is American—and not all American outcomes are made in America.
Hat tip: the excellent Stephen Landry.
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