From the WebMD Archives

May 25, 2021 -- A study found that two doses of the Pfizer/BioNTech or the Astra/Zeneca vaccine protect against the COVID-19 variant first detected in India -- as well as the variant first found in the United Kingdom.

The study emphasized the need for two doses, saying one dose of the vaccines provided much less protection.

The Public Health England study looked at health data from 1,054 people of different ages and ethnicities in April and May.

The study said the Pfizer vaccine was 88% effective against the B.1.617.2 variant, first found in India, 2 weeks after the second dose. The Pfizer vaccine was 93% effective against the variant found in the U.K., known as B.1.1.7, two weeks after the second dose.

Two doses of the AstraZeneca vaccine were 60% effective against the B.1.617.2 variant and 66% effective against B.1.1.7, the study said.

But one dose didn’t work nearly as well, the study said. Three weeks after the first dose, both vaccines provided only 33% effectiveness against B.1.617.2 and 50% effectiveness against B.1.1.7.

The study concluded, “After 2 doses of either vaccine there were only modest differences in vaccine effectiveness with the B.1.617.2 variant. Absolute differences in vaccine effectiveness were more marked with dose 1. This would support maximizing vaccine uptake with 2 doses among vulnerable groups.”

Jenny Harries, the chief executive of the U.K. Health Security Agency, hailed the study as the "first real-world evidence of vaccine effectiveness" against the variant, according to the BBC.

“This evidence is groundbreaking & shows how important the 2nd dose is to secure the strongest protection against COVID-19,” U.K. Health Secretary Matt Hancock said in a tweet. “Thank you to the scientists & clinicians who've been working to produce this research. It’s vital to get both jabs.”

The study authors said the different effectiveness of the vaccines after two doses might be explained by the earlier rollout of the Pfizer vaccine.

The BBC said the Moderna vaccine has also been used in the U.K. since April, but the numbers were too small to be included in the study.

Health experts say the B.1.617.2 variant is one of the main reasons India is having a difficult time bringing the pandemic under control.

India now has the second most confirmed coronavirus cases in the world (26.7 million, behind the United States’ 33.1 million) and the third most deaths (303,000; behind 590,000 in the U.S. and 449,000 in Brazil).

B.1.1.7 is now the dominant strain in the U.K.

Show Sources


Public Health England: “Effectiveness of COVID-19 vaccines against the B.1.617.2 variant.”

BBC: “Covid: Pfizer and AstraZeneca jabs work against Indian variant -- study.”

Twitter: @MattHancock, May 23, 2021.

© 2021 WebMD, LLC. All rights reserved. View privacy policy and trust info