A second booster shot: Cmpanies are developing a so-called bivalent booster vaccine that combines an omicron-specific booster shot with earlier versions

A 2nd booster may come this fall. It might not be the same shot you got last time. Moderna is developing a so-called bivalent vaccine that combines an omicron-specific shot with the company’s original Covid-19 vaccine. NBC News

If another Covid-19 booster shot is needed this fall, it might not be the same shot you got the last time.

U.S. health officials say that coronavirus cases could pick up again in the colder months, and scientists are continuing to evaluate whether another dose will be needed.

If Pfizer-BioNTech or Moderna get their way, the next round of vaccines will contain a new formulation that targets the supercontagious omicron variant, or perhaps two strains of the coronavirus, instead of just one.

The world is going to need an updated Covid vaccine this fall, one that's “tuned to the right combination of variants,” Moderna Chief Medical Officer Dr. Paul Burton told NBC News.

Omicron-fueled Covid cases are continuing to decline in the United States and other parts of the world. Still, the coronavirus is likely here to stay, with Covid probably becoming a seasonal virus, similar to influenza, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, and other top health experts suggest.

No one knows what the predominant circulating variant will be in the coming months, but scientists, including those at the World Health Organization, say the current vaccines may need to be updated to ensure they continue to provide a high level of protection against severe disease and death.

The existing booster shots in use, from Pfizer and Moderna, are still formulated to target the original form of the coronavirus identified in late 2019.

Moderna thinks the dominant strain this fall could be a familiar one: omicron, delta or a descendant of either of the two. ...

"Both Moderna and Pfizer are testing new omicron-specific shots, which have already begun trials and could be ready by the fall. ...