Once fully vaccinated, Pfizer-BioNTech's and AstraZeneca's COVID-19 vaccines are effective against B.1.617.2, a more transmissible variant first detected in India, the U.K.'s public health agency announced May 22.
Research led by Public Health England found Pfizer's vaccine was 88 percent effective against symptomatic infection from the variant two weeks after the second shot. For comparison, the shot is 93 percent effective against B.1.1.7, the dominant strain in the country.
AstraZeneca's vaccine demonstrated 60 percent effectiveness against symptomatic disease from the variant in India, compared to 66 percent protection against the B.1.1.7 variant.
The study involved 1,054 people who were infected with the B.1.617.2 variant between April 5 and May 16.
Three weeks after one dose, the vaccines offered just 33 percent protection against symptomatic infection from the variant, underlining the importance of the two-dose schedule, experts said.
"We expect the vaccines to be even more effective at preventing hospitalization and death, so it is vital to get both doses to gain maximum protection against all existing and emerging variants," said Dr. Mary Ramsay, head of immunization for the U.K.'s public health body.