Measles Resurgence and the Cost of Vaccine Gaps

Measles is extraordinarily contagious. A single case can infect up to 12 to 18 susceptible people, which is why very high vaccination coverage is needed to keep it from spreading.

The MMR vaccine is highly protective: two doses are about 97% effective at preventing measles. The United States declared measles eliminated in 2000, but outbreaks return whenever local coverage slips below the roughly 95% needed for herd immunity.

The stakes are not trivial. Measles can cause pneumonia and encephalitis, and rarely a fatal degenerative condition years later called subacute sclerosing panencephalitis.

For clinicians, resurgence is a reminder to check immunization status at every opportunity and to counsel families clearly. Protecting the vulnerable depends on the immunity of the many.