Dear Dr. Roach: In a recent column on the measles vaccine, you wrote: “Older people may lose immunity, and some people born between 1963 and 1967 may have received an inactive vaccine.” Wait, what?! How do we know if we were not properly vaccinated, and what should we do about it? — L.T.

Answer: There were two types of measles vaccines available between 1963 and 1967. One type was a live, attenuated vaccine, and there were three strains given: the Schwarz, Edmonston B and Moraten strains. If given on or after the 1st birthday, these strains continue to provide lifelong immunity.

A second, killed vaccine was available only during those years, and was frequently given as a series of two or three injections. People who received the killed vaccine are at risk for developing a condition called atypical measles (an immune-mediated disease with high fevers, rash, and frequent lung symptoms) if they are exposed to a person with measles.

If you have your original vaccination record, it should say what type of vaccine you received. If it doesn’t, or if you received killed vaccine, you should consider yourself inadequately vaccinated. High antibody titers by blood testing is not sufficient.

Not everybody who is inadequately vaccinated needs to run out and get the vaccine. However, people planning international travel (there are several areas of measles outbreaks in Europe) or people who are in an area of the United States with measles outbreaks (New York and New Jersey had outbreaks in 2018) and at high risk for exposure (including first responders) should be revaccinated with two doses of MMR vaccine (there is no single-dose measles vaccine).