20 to 30% have some form of complications, it's particularly severe in the vulnerable, very young, very old and compromised immune systems.

https://www.alabamapublichealth.gov/blog/2025/02/sho-march.html#%3A%7E%3Atext=Twenty+to+30+percent+of%2Ceasy+for+measles+to+spread.

I don't think that includes the general weakened immune system that a lot of people experience after the measles, children apparently lose 12 to 73% of their antibodies following a mild measles infection.

https://www.cidrap.umn.edu/measles/measles-does-long-term-damage-immune-system-studies-show#%3A%7E%3Atext=After+severe+measles%2C+children+lost%2Cover+similar+or+longer+durations.

it's highly transmissible, 9 out of 10 people who are exposed and unvaccinated will get it.

https://www.idsociety.org/public-health/measles/know-the-facts/

there are a ton of stats and a ton of complications that can occur with measles, so it's difficult to find one comprehensive number for everything, but everyone who is unvaccinated will probably get it after less than 90% of the population is vaccinated, 20 to 30% will develop complications, a lot of those are going to be permanent. and even the temporary complications can last for years.

We don't have more recent data because it was eradicated so rapidly in 3 years after the vaccine was introduced, but prospects sure don't look good for dumb families and whichever population they're poisoning.