COVID vaccines: The difference between a 3rd shot and a booster

DETROIT (FOX 2) - Some people are getting their COVID-19 vaccine boosters and others are getting their third shot. 

While they may seem like the same thing, they aren't.

Dr. Robert Dunne, the chief medical consultant City of Detroit explains that a booster is a shot given six months after the Pfizer vaccine. The booster is needed because immunity can start to fade after so long.

Related: Pfizer seeks FDA authorization of COVID-19 vaccine for kids 5 to 11

Right now, the Pfizer booster is the only approved booster. It is available for people older than 65. People 18-65 can get the booster if they have underlying health conditions or a job that is considered high risk.

If you received the Moderna vaccine, you cannot get the Pfizer booster. However, you could get a third shot.

The third shot is for certain people whose immune systems are compromised. People who are not immunocompromised do not need a third shot.

"The thought for the people who need that third shot is that they didn't get a good reaction to the second shot because of some underlying medical conditions," Dunne said.

If you believe that you may need a third COVID-19 shot because you are immunocompromised, speak with your doctor.