FDA authorizes additional COVID booster shots for some

The Food and Drug Administration on Tuesday authorized a second COVID-19 booster dose for people 50 and older in an effort to increase protection against serious outcomes of the virus for people at higher risk. The Centers for Disease Control and Prevention recommended the additional boosters. 

The FDA's authorization means people can get another dose of the Pfizer or Moderna vaccines at least four months after their previous booster.

The agency also authorized additional boosters for people 12 and older with severely weakened immune systems. 

Here's what you need to know about who is eligible, when, and why.