Here’s something I didn’t expect to be writing in 2026: measles is back. This is a disease the US basically beat in the year 2000. We “eliminated” it. And now it’s spreading again.
According to the CDC, the US had more than 2,200 measles cases in 2025, the worst it’s been in decades, and there were deaths, all in people who weren’t vaccinated. The reason is simple and pretty scary. Vaccination coverage among kindergartners dropped from about 95% a few years ago to around 92.5%, which left roughly 286,000 little kids unprotected. That gap matters more than it sounds.
This is where a concept called herd immunity comes in, and it’s basically a team-defense idea. Measles is one of the most contagious diseases on the planet. One sick person can infect 12 to 18 other people. The only way to stop it is for almost everybody to be covered, because that protects the people who can’t get vaccinated, like newborns and kids going through cancer treatment. The CDC says you need over 95% of a community vaccinated for that wall to hold. Drop below that and gaps becomes bigger.
Think of it like a zone defense in basketball. If everybody covers their spot, nothing gets through. But if even a few people stop boxing out, suddenly there’s a lane straight to the rim. The good news is the MMR vaccine is about 97% effective with two doses. The tool works, and we just have to use it.
Volunteering in a hospital made this real for me, because I’ve seen that the people most at risk are usually the ones who can’t protect themselves. Herd immunity is how the rest of us cover for them.
Vaccines only work as a team. Herd immunity holds the line, but only if enough people show up.
The Global Pulse 