With measles cases flaring up in many parts of the world, including the US, more people are becoming sharply aware of the importance of vaccinations. However, it’s important to note that some vaccinated adults in the US – namely those who received a measles shot in the '60s – might still be at risk of illness and may require revaccination. Here’s everything you need to know.
The measles vaccine was introduced to the US in 1963. One early incarnation of the shot, called KMV, introduced a dead inactivated measles virus into the body. Just like other vaccines, it was designed to spark up the immune system to produce antibodies against measles, thereby protecting them from the disease.
However, the KMV dead virus shot proved to be ineffective in some cases and could result in atypical measles, an illness characterized by fever, pneumonia, swelling, and “water on the lungs”. This shot was replaced in 1968 with a more effective vaccination that introduced live measles into the body. As such, the US Centers for Disease Control and Prevention (CDC) say that people who were vaccinated before 1968 with either inactivated measles vaccine (KMV) or measles vaccine of unknown type should be revaccinated with at least one dose of live measles vaccine.
“This recommendation is intended to protect those who may have received killed measles vaccine, which was available in 1963-1967 and was not effective,” according to the CDC.
It’s also worth remembering that you don’t need a vaccination if you were born before 1957 as it’s presumed your immune system came into contact with the virus and you have acquired immunity. As another side point, this information is only relevant to people in the US in the 1960s. Different health agencies across the world have varying practices, however, generally speaking, KMV and inactivated measles virus vaccines were not widely used across the world.
What Should You Do If You Were Vaccinated Between 1963 and 1967 in the US?
An estimated 600,000 to 900,000 Americans received the ineffective vaccines from 1963 to 1967. However, chances are, you probably don’t remember what type of shot you received in the 1960s. You can track your medical records through a doctor, your previous employers, your high school health services, and family documents, but it’s not unusual to lose this information as there is no centralized organization that keeps all the records. You can also have a blood test to determine whether you’re immune, although this can often cost more.
If you are unsure, it’s certainly better to be safe than sorry. The CDC notes: “There is no harm in getting another dose of MMR vaccine if you may already be immune to measles (or mumps or rubella).”