When the measles shots first came out, there were different types: the version containing “live” virus, which is still in use today, and the “killed” or inactivated measles vaccine, which was withdrawn in 1967 because it quickly lost its effectiveness over time. In fact, in a 1965 study, only one quarter of the children given three doses of the “killed” vaccine over a three-month period still had measles antibodies a year later. And even after a yearly booster injection, 43 percent of children exposed to measles developed it.
The CDC recommends that people who were vaccinated prior to 1968 with either inactivated (killed) measles vaccine or a measles vaccine of unknown type should be revaccinated with at least one dose of live attenuated measles vaccine.
The only way to know which vaccine you received is by looking at your medical records. If you don’t have specific documentation, consider getting a shot.
Large-scale measles vaccinations began in 1963, but it wasn’t until 1989 that the American Academy of Pediatrics began recommending that two doses of the live vaccine be given to children after their first birthday. That’s because if you get one dose, it’s 95 percent likely to be effective — but with two doses it’s 99 percent effective. In 1989 — and this still stands today — health officials determined that kids either be given this second “booster” shot between ages 11 and 12, or when they enter school between ages 4 and 6 years.
In 1989, 11 and 12 year olds were born in 1977 and 1978 — so anyone born from those years forward probably got a second dose of the vaccination as a kid. You may have also received a second shot if you’re a healthcare worker, travel internationally, or went to college. But given this data, people born before 1978 should check their medical records.