Do Adults Need a Measles Shot?
SAN FRANCISCO – Measles, which authorities thought was eliminated as a public health threat in the United States in 2000, has re-emerged in increasing numbers this winter. Through March 14, the Centers for Disease Control and Prevention (CDC) has reported 268 individual U.S. cases—73 of them in Washington state, in a community where only 78 percent of the school-aged population is vaccinated.
By comparison, the CDC reported a total of 372 cases of measles during 2018.
In California, this year’s CDC figures include five Bay Area residents (three adult, two pediatric) in Santa Clara, San Mateo, San Francisco and Santa Cruz counties who have contracted measles. Two of these cases were contracted from another person on an airplane flight.
In the past, many thousands of Americans developed measles each year. Many would die, and many more would develop complications such as pneumonia and encephalitis.
“We have fewer deaths now because of the vaccine—and only because of the vaccine,” says Jeffrey Silvers, M.D., Sutter Health’s medical director of Pharmacy and Infection Control.
Measles is a ferociously contagious disease: The number of cases one case generates on average over the course of its infectious period is 10 to 18, compared with two or 3 for influenza.
“The only treatment for measles is prevention,” says Dr. Silvers. “Vaccination keeps you from developing the disease but also from spreading the virus. When immunization lags, outbreaks can occur. After all, many people move to America from countries without immunization programs, and global travel in general increases the chance of measles spreading to vulnerable populations.
“The vaccine works well. Two doses are about 97 percent effective at preventing measles. One dose is about 93 percent effective.”
So do you need the vaccine now if you received it as a child?
Two doses of the vaccine are required for people embarking on international travel, says Dr. Silvers—and for healthcare workers as well as people who received the inactive vaccine used from 1963 to 1967.
“Everybody else only needs one dose,” he says. “If you have been properly vaccinated, you don’t need to get it again.
“But if you received the vaccine as a child during the early to mid-1960s, you should discuss with your physician the possibility of receiving it again.”