Here is some information about measles taken from the CDC webpage.
1. The majority of those who got measles were unvaccinated.
2. Being fully vaccinated means getting two doses of MMR.
3. It presents as a fever and characteristic rash
4. The incubation period is 7-18 days, so if someone was exposed to a known measles case (or even a questionable one), and they haven’t developed a rash 3 weeks later – they don’t have measles.
5. Measles is passed by respiratory droplets and is very contagious to those who are not immune.
6. The measles vaccine wasn’t developed until 1963, so those born prior to that probably got the disease and are now immune, despite not receiving the vaccine.