Measles: What you need to know about vaccines, outbreaks and staying safe
Once considered eliminated, measles is again on the rise with more cases this year already than in all of 2018.
Several incidents of measles in the Bay Area, including the recent case of a San Mateo resident at Google headquarters, have many wondering if they are at risk of getting infected. Here are some frequent questions about the highly contagious virus, the vaccine and what to do if you are exposed to measles with answers provided by the CDC. Health experts agree that the key to preventing outbreaks is getting more people vaccinated.
"Measles can cause serious illness and even death," says Dr. Jonathan Blum, chief of infectious disease at Kaiser Permanente Santa Clara. "Because measles is so contagious, we need to have a high level of immunity in the community in order to prevent ongoing transmission of the virus. Unvaccinated people are like 'fertile ground' for the spread of the virus—if there are enough of them, the virus will continue to spread."
Q: What are the symptoms?
A: Measles starts with a fever that can get very high. Some of the other symptoms include cough, runny nose, diarrhea, and ear infection. Three to five days after symptoms begin, a red rash breaks out.
Q: How is measles transmitted?
A: Measles spreads when an infected person breathes, coughs or sneezes. It is very contagious. You can catch measles just by being in a room where a person with the virus has been—up to 2 hours after that person has left. And you can catch measles from an infected person even before they have a rash. Almost everyone who has not had the MMR vaccine will get measles if they are exposed to the virus.
Q: I think I've been exposed to someone who has measles. What should I do?
A: Call your doctor to determine if you are immune to measles based on your vaccination record, age or laboratory evidence. If you don't have your vaccination record, the doctor can make special arrangements to evaluate you, without putting other patients and medical office staff at risk.
If you are not immune to measles, an MMR vaccine or a medicine called immune globulin may help reduce your risk developing measles. If you do not get MMR or immune globulin, you should stay away from settings where there are susceptible people (such as school, hospital, or child-care facility) until your doctor says it's OK. This will help ensure that you do not spread the virus to others.
Q: How effective is the measles vaccine?
A: The measles vaccine is very effective. One dose is about 93 percent effective at preventing measles if exposed to the virus; two doses are about 97 percent effective.
Q: Could I still get measles if I am fully vaccinated?
A: Very few people—about three out of every 100—who receive two doses of the vaccine will still contract measles if exposed to the virus. Experts aren't sure why. It could be that their immune systems didn't respond as well as they should have. The good news: Fully vaccinated people who get measles are much more likely to have a milder illness. And fully vaccinated people are also less likely to spread the disease to others, including those who cannot be vaccinated because they are too young or have weakened immune systems.
Q: I was vaccinated as a kid. Do I need a booster vaccine?
A: No. Those who received two doses of the vaccine as children, according to the U.S. vaccination schedule, are considered protected for life. The CDC says they should never need a booster dose.
Q: What if I'm an adult? Would I ever need a booster?
A: It depends. The CDC considers you protected from measles if you have written records showing one of the following: You received one dose of measles vaccine (and you will not be in a high-risk setting); a laboratory confirmed that you had measles at some point in your life; a laboratory confirmed that you are immune to measles; or if you were born before 1957.
Those at high-risk for measles transmission, such as health care personnel and international travelers, should have two doses separated by 28 days.
Q: Why have there been more measles cases in the United States in recent years?
A: CDC experts cite two reasons: First, more Americans are visiting countries—such as England, France, Germany, India, the Philippines and Vietnam—that have seen increases in measles cases. Second, the virus is spreading in several U.S. communities that have pockets of unvaccinated people.
©2019 The Mercury News (San Jose, Calif.)
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