Bill Gates says a third COVID vaccine shot may be necessary to combat variants of the virus. He tells CBS News:
"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."