Moderna

The Biden administration may scrap plans to expand eligibility for second boosters to younger adults. Instead, it's trying to speed up the next generation of boosters targeting the omicron variant.

The "bivalent" vaccine — meaning it targets two different antigens — is Moderna's leading candidate to have an effective booster ready for fall of 2022, the company said.

The Delta variant is the fast-moving strain of the coronavirus now found in 96 countries. It's expected to be the dominant variant in the U.S. within weeks.

In the U.S., more than 1 out of 5 residents is fully vaccinated against COVID-19. But elsewhere in the world, vaccination rates are much lower. Some poor nations have yet to receive a single dose.