What changed was less funding to the agencies that surveil for disease spread so they can intercept outbreaks. The US CDC funded these programs all over the world.
What changed was that they were free-riders on the rest of the population and one day the rest of the population no longer met the threshold.
One could say it is because of the spread of misinformation and that might be the proximate cause.
But if a drug addict periodically overdoses and needs naloxone, and one day a supply chain issue makes it hard to access and he dies, did the supply chain kill him or his drug addiction? Perhaps monocausal explanations are insufficient.
It's a little hard to believe that people who famously don't use computers were infected by an "misinformation", a rather loathsome neologism. There was famously a really serious outbreak in the NYC Orthodox community from 1989 to about 1991. Unvaccinated communities are a sort of immunological tinder box, and you never know when a stray spark might land.
This is the result of a failure of public health to reach out to these religious communities in effective ways for decades.
That stray spark’s survival is heavily influenced by the herd immunity of the rest of the population.
Put another way if the overall population sees an average of 0.5 or 0.95 infections per case there’s zero chance of a huge outbreak. But odds of a case making it to a vulnerable population is wildly higher in the second case.
I'm not sure about Mennonites. One of their communities writes about it and seems to suggest only 1 of the 40 or so communities is hardliners against vaccination. But I also note this is written in a really neutral way (could be to placate government, dunno): https://www.mennoniteusa.org/measles/
Mass immigration from countries where measles is endemic? India has over 10,000 cases per year and makes up the plurality of Canada's immigration intake. Canada has a very high two-shot vaccination rate, but there are pockets like the Mennonite communities that are vulnerable.
Only for stays greater than six months. So an unvaccinated person can fly in from wherever and stay for 180 days legally, or just overstay their visa. That's plenty of time to spread measles.
this is a racist dog whistle. Stop with the "mass immigration" BS.
India, contrary to what the racists believe, has a long and successful vaccination program. A country of 1.5 billion people has around a 70% MMR vaccination rate among infants. Canada's in the 80% range and dropping.
Canada had eliminated measles, it was reintroduced by travel from a country where measles was endemic. This is not rocket science. High-volume international travel from countries where measles is endemic, like India, poses a public health risk to countries that have eliminated the disease. The same goes for tuberculosis, hepatitis, etc.
Oh yeah, the spread of misinformation on the internet.