A third dose of coronavirus vaccine may be needed to prevent serious cases of new variants of the disease, Bill Gates said Tuesday. The billionaire philanthropist’s comments come amid to the growing concern that current vaccines are less effective against the South African and Brazilian variants.

“The discussion now is do we just need to get a super high coverage of the current vaccine, or do we need a third dose that’s just the same, or do we need a modified vaccine?” Gates told “CBS Evening News” anchor and managing editor Norah O’Donnell. 

“All five of the companies that have U.S. vaccines are looking at making that modification and adding that in so that people who’ve already had two shots might need to get a third shot,” he said. “I think it’s reasonably likely that we will have a tuned vaccine just to make absolutely sure that as these variants hit the U.S. that they’re not escaping from vaccine protection.” 

Gates is funding studies in South Africa to determine whether the AstraZeneca, Johnson & Johnson and Novavax vaccines were as effective against the more contagious variant. 

“AstraZeneca in particular has a challenge with the variant. And the other two, Johnson & Johnson and Novavax, are slightly less effective, but still effective enough that we absolutely should get them out as fast as we can while we study this idea of tuning the vaccine,” Gates said. 

If the coronavirus is not eradicated, he said, additional shots may be necessary in the future. “Probably not yearly, but as long as it’s out there, we want as many Americans as possible not to be spreading it to each other,” he said. 

Dr. Scott Gottlieb, the former head of the Food and Drug Administration, told “Face the Nation” on February 7 that he believed the vaccines currently being distributed in the U.S. would offer “reasonable protection” against the new variants, even if they are less effective against the new strains. Still, he said, it may also be necessary for booster shots in the fall. 

This content was originally published here.