The measles virus is resurging in the U.S. despite the long-standing availability of a vaccine that provides nearly life-long immunity. In the past few weeks, hundreds of people were exposed to a child with the virus in a Northern California healthcare facility; our state is one of 17 jurisdictions with reported measles cases in 2024, higher than seen in recent years.
Measles is an extremely transmissible pathogen: On average, one infected person infects 12 to 18 unvaccinated people. The airborne virus can linger in floating aerosols long after someone has left a room, and the common symptoms, which include rash, a high fever, watery eyes, cough and a runny nose, typically take a week or two to appear.
Infections can also cause immune amnesia, in which your immune system becomes better at fighting measles and worse at fighting other infections you were previously protected against. In rare cases it also leads to death, more often in children than adults, from respiratory or neurological complications, including a type of brain swelling in young children that can appear years after the initial measles infection.
Before the measles vaccine was introduced and licensed in 1963, the Centers for Disease Control and Prevention cites an annual average of 549,000 cases (with likely millions more going unreported), 48,000 hospitalizations, nearly 500 deaths and 1,000 people with chronic disability. By 2000, thanks to vaccination, measles was declared eliminated in the U.S. But because of cases from people arriving here from other countries, combined with pockets of low vaccination, we are seeing outbreaks among unvaccinated people.
Policy can worsen the issue. Last month in Florida, following an outbreak at an elementary school, the state’s surgeon general left the decision to parents whether to send their children to school, citing high levels of community immunity as the rationale for not following the usual protocols. That cavalier response risked a much worse…