I’m sure you’ve already heard, but Texas is having a nasty measles outbreak right now. My eight-month-old is in day care, and she isn’t due to get the measles vaccine until 12 months. Can she get it early? I want to do what my doctor recommends, but I’m very worried about this.
—Nervous Texas mama
The short answer is that, yes, it may be a good idea to get your eight-month-old vaccinated early. But let’s step back to better understand this.
During pregnancy, infants acquire measles antibodies from their mother (assuming mom has either been vaccinated or had measles). For the first six months of their life, these antibodies are active, but they decay over time. In the case of measles, having maternal antibodies interferes with the response to the vaccine (this isn’t true of all viruses and vaccines). This means if you vaccinate too early, some kids will not develop their own immune response, and the vaccine will not provide lasting protection.
The recommended age of first measles vaccination has varied over time. Early on, first vaccines were given before nine months of age, but over time more information came out suggesting that might be too early and that many children still had maternal antibodies at that point.
A trial published in 2004 went a long way toward settling the overall question of timing. In it, researchers randomized about 1,000 children into receiving the measles vaccine at 9 months, 12 months, or 15 months. The main outcome they studied was whether the child had a vaccine response.
What they found was that 87% of children vaccinated at 9 months responded to the vaccine, versus 95% of those vaccinated at 12 months and 98% who were vaccinated at 15 months. This paper led to the general recommendation that the first vaccine happen between 12 and 15 months.
A second measles vaccine is recommended around age 4 — this second dose captures any children who did not respond to the first, or had a low response. The second dose can be done sooner, but it’s common to do close to school entry.
So in the absence of an outbreak of measles, the first dose between 12 and 15 months makes sense. Doctors differ in their exact timing, and based on the numbers above, it doesn’t matter too much.
However, in the presence of an outbreak or international travel to an area with endemic measles, it is recommended that a child get vaccinated as early as six months. This is because while it is possible that they still have maternal antibodies, there is a good chance those have declined. The vaccine at this point can provide protection, and if there is a real risk of measles exposure, it is a good idea. If you do vaccinate your child at this age, it is recommended that another dose is given at 12 to 15 months, in case they did not respond to the first. In this case, your child would get a total of three doses.
In conclusion: This is certainly worth talking to your doctor about. Even if they routinely give the vaccine at 12 months, there is a good chance that there is flexibility in the case of an outbreak. We know the vaccine is safe for children in this age group, because this used to be the age at which it was commonly given. Good luck and stay safe.
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Thank you, this is really helpful! For kids between 1 and 4-ish, when should we consider getting the second dose early?
For premies, is the 6 month time point based on actual age or corrected gestational age? I assume actual since all other vaccines have followed actual age, but just wanted to clarify.
I didn’t show an immune response to measles while pregnant, but received an MMR vaccine when my daughter was 9 weeks old. Can she receive immunity via breastmilk or is there only transfer in utero? We live in Pennsylvania but plan to travel to Texas in April to visit family. She won’t yet be 6 months. We’re trying to decide if we should reconsider our trip, wait and see, or talk to our pediatrician about early vaccination.
Passive immunity through breastmilk is limited. This is a tough choice, but probably depends on where in Texas you are going, and what the situation is at the time. They will not vaccinate before six months.
What is the difference in total efficacy of the three dose series? In the two dose it seems as though it catches 100% but what about the early 3 dose group?
Its the same. The changes over time are about picking up people who didn’t respond the first time. In the three dose plan, a larger share of children do not respond to the first dose. You pick up most of them at the second dose, and then the rest at the third.