The short answer is, obviously, to make sure you’re all vaccinated. But vaccination schedules can have variations and there are a few factors at play. Given the current measles scare, I wanted to make sure my family was doing all we could to protect ourselves, as this is what I found.
First, why are we talking about measles? Because there’s an outbreak right now. According to the CDC, in January 2019, seventy-nine cases of measles were confirmed, across ten states. There have been outbreaks (defined as 3 or more cases) in New York State, New York City, and Washington State, associated with travelers coming back from Israel and Ukraine. [Update as of April 10, 2019: There are now 228 cases just in Williamsburg, and 285 in Brooklyn, NY overall, which have prompted the city to declare a state of emergency and institute mandatory vaccines, with fines for non-compliance.]
Outbreaks happen when there isn’t herd immunity, when not enough people are immune in a community and the disease starts to spread. The best way to prevent measles is through the MMR vaccine.
Is your family immune?
Babies 0-12 months are probably not immune.
What you can do: Especially if there are measles cases in your area, try to make sure family, friends, and caregivers spending time with your baby are vaccinated. If your baby is in a high-risk context, such as traveling internationally or in contact with many unvaccinated people, it may be worth asking your pediatrician about getting vaccinated before the standard 12-15 months. Early vaccination for babies 6-11 months is recommended by the CDC for babies traveling internationally or in an epidemic situation.
Details: Babies often have some “passive immunity” due to antibodies received from their mother in utero or through breastmilk, but most babies likely don’t have enough to protect them from the disease. Babies can, however, be vaccinated before 12 months. It’s not harmful but is simply less likely to be effective, because a baby’s low-level passive immunity can prevent them from reacting to the vaccine with a sufficient immune response to become protected. Note that babies immunized before 12 months will likely still need two additional shots in the future at the usual ages. It can be an extra step to take during an outbreak or in higher-risk contexts, but because the vaccine is less likely to be effective before 12 months, remember that it’s not a substitute for avoiding crowds and people who may have the measles.
Adults and children over 1 year are probably immune, by two weeks after their first MMR shot.
What you can do: Check your medical records to make sure both doses of the MMR vaccine have been given on schedule. Check your state’s vaccination laws or databases to confirm the vaccination rates at your children’s schools. If your child is in a high-risk context, such as living in a city with an outbreak, or attending a Waldorf or religious school without herd immunity, you could ask your pediatrician about getting the second shot earlier. If your child has a medical condition that means they can’t get the MMR vaccine and there are measles cases in your area, you may want to make sure that anyone in regular contact with them is vaccinated.
Background: Current CDC recommendations are for two doses. The first dose, typically given between 12 and 15 months, is effective in causing immunity for 93% of people. With the second dose, typically given between 4 and 6 years of age, 97% of people become immune. Here’s the thing: the second shot can be given earlier than 4 years, as long as it has been at least 28 days since the first shot. Waiting until age 4 to 6 has more to do with “administrative considerations,” that is, so that immunizations required for school attendance can be conveniently given and recorded all at once. So it’s possible to ask about getting the second shot early; just know that your child may still need another shot before attending school and that the additional shot may not be covered by your insurance.
And yes, you can get a blood draw to check whether measles antibodies are present. If I were considering optional travel to a place with a current measles outbreak (at the time of posting, that’s Israel and Ukraine, but you can check current travel notices here), I might get the blood draw done to see if I have immunity or not. Otherwise, though, if you’re getting a needle anyways, your doctor may suggest that you just get an MMR booster instead.
Who needs a booster?
Measles immunity is considered to last for life, so anyone who has received two shots should not need another. According to the CDC, you will be assumed to be adequately vaccinated if any one of the following applies:
- one or more doses of a measles-containing vaccine administered on or after the first birthday for preschool-age children and adults not at high risk
- two doses of measles-containing vaccine for school-age children and adults at high risk, including college students, healthcare personnel, and international travelers
- laboratory evidence of immunity (blood draw/titer)
- laboratory confirmation of measles
- birth before 1957 (note: this is because the vaccine was introduced in 1963, so people born in 1957 or earlier almost certainly have been exposed to measles already.)
The vaccine isn’t old enough for lifetime immunity to be completely assured, however, so if you’re concerned, check with your doctor about getting a titer (blood draw) or booster shot.
Looking for data? Each state has different vaccination laws, but you can get a snapshot and click through to details on each state here. If you’re curious about state legislative changes, you can find those here. In California, you can check vaccination rates at all daycares and preschools, elementary schools, and middle schools. California vaccination rates have gone up since 2016, when a new law banning personal belief exemptions came into force, but there are still schools where there is not herd immunity. You can also check school vaccination rates for other states, including Texas, New York, Pennsylvania, and Washington.
You can also check out the New York Times’ measles explainer, published on February 20, 2019.
Disclaimer: I’m not a physician, just a worried parent. Check with your doctor!
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