Clark County Public Health has reported that a child who received a single vaccination for measles had contracted the disease, bringing the number of confirmed measles cases to 42 as of Friday.
It is the first confirmed case in the outbreak that had the MMR vaccination. Of the remaining confirmed cases, 37 people were unimmunized and vaccination records for four others are unverified.
Clark County Public Health Director Dr. Alan Melnick said he isn’t surprised to see a vaccinated case appear because the outbreak is growing so large.
“When you get enough cases you may see measles in a vaccinated person,” Melnick said. “The risk in a vaccinated person is still far less.”
One dose of the MMR vaccine is 93 percent effective, and two doses are 97 percent effective, according to Public Health, which recommends two doses of the vaccine.
Melnick confirmed the child who contracted measles, despite receiving the single dose, got the vaccine well before contracting the disease. The vaccine can still be effective if administered within 72 hours of exposure to measles but is usually less effective than getting the vaccine beforehand.
According to the Centers for Disease Control and Prevention, experts aren’t exactly sure why the MMR vaccine isn’t 100 percent effective, but one theory is that a person’s immune system doesn’t respond as well to the vaccine as it should. The CDC considers two doses of MMR to be good enough to protect someone for life — booster vaccinations aren’t necessary.
Melnick said people who are fully vaccinated and contract measles generally experience milder symptoms than those who are unvaccinated, and they are less likely to spread the disease. Vaccination is the best way to protect against measles, he said.
“It’s not perfect, but it’s pretty darn good,” he said.
Of the confirmed Clark County cases, 31 are between the ages of 1 and 10; 10 are between 11 and 18; and one is between 19 and 29.
Since the outbreak started, there has been one confirmed measles case in Multnomah County, Ore., and another in King County. There has also been an exposure in Bend, Ore., but no confirmed cases in that area yet. Two Clark County cases traveled to Hawaii recently, but most likely didn’t create any exposures during their trip, according to Public Health.
Dozens of stores, health care facilities and schools have been deemed exposure sites. Click here for a complete list.
What to do if you might be infected
The Centers for Disease Control and Prevention reports that 90 percent of unvaccinated people exposed to the measles virus come down with the disease. The virus lives in the nose and throat mucus of an infected person, and can survive for up to two hours in an airspace where the infected person coughed or sneezed.
Health officials are urging anyone who has been exposed at an identified location and believes they have symptoms of measles to call their health care provider prior to visiting the medical office to make a plan that avoids exposing others in the waiting room.
If you are unsure of your family’s immunization status, you can view, download and print your family’s immunization information online at MyIR.net or request a copy of your immunization record from the Washington State Department of Health.
Anyone with questions about measles infection or the measles vaccine should call their primary care provider or a county health department:
- Clark County Public Health, 360-397-8021.
- Multnomah County, Ore., Public Health, 503-988-3406.
- Washington County, Ore., Public Health, 503-846-3594.
- Clackamas County, Ore., Public Health, 503-655-8411.
Clark County Public Health has been regularly updating its list of locations where people may have been exposed to measles. There are dozens of locations in total, including hospitals, Portland International Airport and multiple schools.
Public Health has established a call center for questions related to the investigation. Anyone who has questions about public exposures should call 360-397-8021. The call center is open daily.
For a complete list of exposure sites, visit the Public Health measles investigation webpage at www.doh.wa.gov/YouandYourFamily/IllnessandDisease/Measles/MeaslesOutbreak.
Measles symptoms begin with a high fever, cough, runny nose and red eyes, followed by a rash that usually begins at the head and spreads to the rest of the body. A person can spread the virus before they show symptoms.
People are contagious with measles for up to four days before and up to four days after the rash appears. After someone is exposed to measles, illness develops in about one to three weeks.