Photo of a single dose of the MMR vaccine. (Photo by Joshua Haiar/South Dakota Searchlight)
State health officials declared a measles outbreak Thursday following five confirmed cases in Oregon.
Dr. Howard Chiou, medical director for communicable diseases and immunizations for the Oregon Health Authority’s Public Health Division, warned during a virtual press conference Thursday morning that those cases likely represent a fraction of the actual numbers in the state. That’s because not everyone who catches measles will seek medical attention, Chiou said.
“What I really want families to hear is that measles is here in Oregon,” Chiou said. “Cases are rising across the United States. And people should really reconsider their vaccine decisions and talk to their health care providers to make sure that they and their families are getting the protection that they need.”
A new data dashboard the Oregon Health Authority published Thursday shows how the measles virus has spread through Oregon counties, based on wastewater surveillance. Health officials take samples from community sewage to check for the measles virus, as they do for other diseases.
They’ve detected traces of the measles virus in multiple parts of the state, though the confirmed cases were in Clackamas and Linn counties. During the past two weeks, according to state data, wastewater surveillance has found low levels of the measles virus in Lincoln, Linn, Marion, Clackamas, Multnomah and Morrow Counties.
Doctors typically recommend the two-dose measles-mumps-rubella (MMR) vaccine starting at 12 months old, with the second dose between 4 and 6 years old. Approximately 97% of individuals who receive the two doses develop immunity to measles, according to the American Academy of Family Physicians.
While breakthrough infections in vaccinated people are rare, the disease is highly contagious to unvaccinated people — approximately nine in 10 susceptible people who are in close contact with a contagious measles patient will contract it. Of the five cases in Oregon this year, health officials confirmed that four were not vaccinated and do not yet know the vaccine status of the fifth.
“Measles is not just a fever and a rash. All children who get measles are absolutely miserable,” said Dawn Nolt, an infectious disease doctor at Doernbecher Children’s Hospital.
Symptoms can begin up to three weeks after exposure and can include fever, flu-like symptoms and a telltale rash on the face that spreads to the rest of the body.
Nearly one-third of people infected with measles develop complications, such as ear infections, pneumonia and encephalitis, or brain swelling. The disease also makes it harder for patients’ immune systems to fight back against other diseases for months or years after infection.
The respiratory virus spreads through the air when an infected person speaks, sneezes, coughs or breathes. It can linger in the air for up to two hours.
Health officials have a goal of a 95% vaccination rate to limit the spread of the disease and protect infants and people who can’t be vaccinated through herd immunity. Oregon requires children attending public schools to be vaccinated against measles, as well as other diseases including diphtheria, chickenpox and polio, but widespread use of medical and nonmedical exemptions means the state hasn’t met that goal.
Last year, the health authority reported that 93.5% of kindergarteners had received their first dose of the MMR vaccine and 90.5% had received both doses. The state’s nonmedical vaccine exemption rate was the highest it had ever been, with nearly 10% of kindergarteners receiving an exemption for nonmedical reasons for one or more required vaccines.
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