The Centers for Disease Control and Prevention is advising people with compromised immune systems to get a third dose of the vaccine, but the rest of Americans may soon be able to get a third shot as well.

The shot is available at hundreds of CVS and Walgreens locations across the state for those who are moderately or severely immunocompromised.

St. Vincent's Medical Center infectious disease specialist Jo-Anne Passalacqua says the potential third dose is important.

"It's always true that when immunocompromised people receive vaccines, they don't receive the same robust response to vaccine that healthy people do. And so the concern with the delta variant, which is much more infectious, that we ensure that our immunocompromised are well-protected," she says.

U.S. health officials are expected to recommend vaccine boosters for all Americans 12 and up eight months after their second dose of the Pfizer or Moderna vaccine. The announcement could come as early as this week.

Passalacqua anticipates the formula for the third dose would be the same as the first and second but that down the road that would change for any additional shots.

"The concept there being very much like a flu shot. That's modified each year for the common circulation strains of the flu virus."