June 8, 2021 -- The highly infectious and potentially more deadly COVID-19 variant that originated in India is now the dominant strain in the United Kingdom, a trajectory health officials are working to prevent in the United States, top coronavirus expert Anthony Fauci, MD, said at a news conference Tuesday.
Variant B.1.1.7 was previously the most common strain in the U.K., where it originated. Now, Delta, also known as B.1.617.2, accounts for a majority of U.K. cases. The Delta variant accounts for 6% of sequenced cases in the U.S, while B.1.1.7 remains the dominant strain.
“The Delta variant has been reported in 60 countries, including the U.K. and USA. Clearly now its transmissibility appears to be greater than the wild-type alpha variant,” Fauci said. “In England, B.1.1.7 was dominant, and then [Delta] took over. We cannot let this happen in the United States.”
Delta’s transmission is also peaking in younger groups abroad, specifically people ages 12-20, Fauci said.
He called Delta’s high transmissibility a “powerful argument” to get vaccinated and restated the administration’s goal of getting 70% of the U.S. at least partially immunized by July 4.
Fauci cited research showing that both the Pfizer and the AstraZeneca vaccines protect against the Delta variant.
A Public Health England study examined health data from 1,054 people taken in April and May and found the Pfizer vaccine was 88% effective against Delta, while AstraZeneca was 60% effective.
Fauci stressed the importance of getting the second shot. Just one dose of the Pfizer vaccine was only 33% effective.
“If you've gotten your first dose, make sure to get that second dose,” Fauci said. “For those who have not been vaccinated, please get vaccinated.”
Fauci said there is research under way on the use of boosters for both the original COVID-19 virus and the variants, but did not specify when they may be available.