People born between 1957 and 1989 may be under-vaccinated for measles and not know it, according to the Centers for Disease Control and Prevention, and some doctors are recommending they receive another dose of the vaccine.

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The CDC said Monday that a record 704 cases of the disease has been confirmed in 22 states, the largest outbreak since 2000 when the disease was effectively eradicated.

The agency said at least 10% of confirmed cases are in people who have already had the vaccination.

Some people have said they don’t think about the vaccine unless they’re dealing with children,

Dawn Laird explained, “I didn’t know about it. When you were older, I thought it was when you were younger (one gets the vaccine and) it works throughout when you’re growing.”

Doctors said depending on when you got the shot, it might not be enough to protect against the virus.

Until 1989 the CDC only recommended one dose of the vaccine.

According to the agency, a single shot is 93% effective, compared to 97% for two doses.

The CDC also said some earlier versions of the shot weren’t as effective.

The agency suggested those who received the vaccine before 1989 get a booster.

Stephen Williamson said, “I don’t think it’s necessary, but they say that it’s not harmful to get a booster shot. If you want to be absolutely safe I’d recommend you go ahead and get a booster.”

"I don't know that I'd go out just to do that (unless) ... it happens to be there," Laird said.

Health experts are warning that people who were vaccinated for the measles before 1989 may need a booster shot.

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Credit: Wikicommons