Submitted by Ed Marcuse
October 26, 2026
As opposed to a current measles outbreak in Pennsylvania that’s rapidly expanding and has topped 1,300 cases, an outbreak in Washington state earlier this year involved multiple imported cases but was limited to 26 infections after a rapid response by local, state, and national officials, according to a Public Health Alerts report published today.
The authors, led by researchers with the Washington State Department of Health and the Centers for Disease Control and Prevention, say that compliance with isolation and quarantine guidance and public health messaging may have helped control the outbreak.
Public Health Alerts, a collaboration between NEJM Evidence and CIDRAP, fills a gap in reliable data, offering expert-reviewed reports that translate frontline observations into actionable public health evidence. An NEJM Evidence editorial explains the initiative further. Read all Public Health Alerts reports here.
Outbreaks underscore how contagious measles is
The first measles importation involved two cases. The index patient developed a rash on January 12 after visiting South Carolina during its large outbreak, which was declared over in August after reaching 997 cases. A close contact also contracted the highly contagious viral disease.
The second importation led to 14 confirmed cases. The first four infections were among people who reported contact with South Carolina residents who had visited Washington while contagious or who crossed paths with the South Carolina travelers. These four developed rashes from January 13 to January 24. Ten secondary cases involved close contacts (nine) or an exposure location (one).
In the third event, two Washington residents developed measles after traveling to South Carolina and were exposed to sick people there. These patients developed rashes on January 15 and 16. No secondary cases were detected.
Most Washington residents with measles followed isolation and quarantine recommendations, which likely helped limit onward transmission.
The fourth importation involved a single person who had traveled out of state. The report doesn’t specify the location of this measles exposure.
The final importation was also tied to South Carolina’s outbreak via whole-genome sequencing of samples from patients. It grew to seven cases in the same county as the fourth importation. The index patient reported a rash on January 19 and visited a school and a healthcare facility while contagious, which led to six additional infections.
Twenty-four of the 26 measles patients were unvaccinated, while the vaccination status of the other two is unknown. None of the patients required hospitalization.
The authors of the report conclude, “Most Washington residents with measles followed isolation and quarantine recommendations, which likely helped limit onward transmission. Public health messaging focused on nonvaccine measles control measures may have improved community acceptance of public health recommendations.”