

It’s a bit of both, or four things, really.
Measles is insanely infectious. Covid has a reproductive number around 4 to 5 depending on urbanisation etc. Measles is generally estimated around 15 in the general population, but numbers go all the way to 200 for children in schools (as in 1 kid infects 200 kids).
The measles vaccine is not perfect. It’s only about 97% effective after 20 years, meaning that if you had the shots, you still have about a 3% of getting measles.
In Canada (and basically everywhere) measles vaccines are given at age one.
And Alberta is full of complete fucking idiots who never got vaccinated. And those absolute morons tend to cluster is “crunchy suburban mom” clusters as well as “far right conspiracy nutcase” clusters.
What ALWAYS happens is some unvaccinated kid gets measles, spreads it to other unvaccinated kids, and you get a small local outbreak. Some random unlucky 3%ers might get caught up, or some even less lucky babies, but generally that’s the end of it. That’s what used to happen, because overall immunity was high, and importantly, the parents of the unvaccinated kids were vaccinated.
Now, the unvaccinated kids from the 90s are having kids. So when a small local outbreak happens, the sick kids bring it home. The parents spread it outside, to their also-unvaccinated friends and THEIR unvaccinated kids, and we’ve got not one outbreak, but a whole bunch.
And that’s where the trouble starts, because 97% immunity is actually damned low. That’s 126000 people in Alberta who can get sick, and that’s much higher than the number of unvaccinated idiots (thank god). But now we’ve got tendrils of measles reaching out anywhere, finding new pockets of unvaccinated idiots where it can pop up.
And there’s a fifth problem. And ironically, that’s the problem that nobody gets measles anymore. If you asked your great grandmother what you should do with a kid who has ten thousand little red bumps, she’d tell you to lock that kid in the bedroom, slide food under the door and keep them away from your other eleven children. If you ask your 28 year old neighbor, she’d probably tell you to rub crème on the poor kids irritated red skin.
People don’t recognise measles anymore. It’s not a scary disease like it used to be. Nobody knows anyone who lost sight or hearing thanks to measles. Nobody knows anyone who lost a child to measles. I don’t even know anyone who knows anyone who has seen measles. And that’s great… Unless your collective health depends on it.
EEEEEEEEEEEEEEEEEEEEEE