Two doses of Covid vaccines provide adequate protection

Two doses of Covid vaccines provide adequate protection

May 25, 2021: -A new study has found that two doses of either the Pfizer-BioNTech or AstraZeneca-University of Oxford vaccine give adequate protection against the Covid variant first discovered in India. However, it underscored the need for two doses, as both vaccines were significantly less effective after only one shot.

The study, led by Public Health England, also found that two doses of the vaccine were similarly effective at protecting against the variant that first emerged in the U.K. and has since become a dominant strain in the West.

Dr. Jenny Harries, CEO of the U.K. Health Security Agency told the BBC that the study provided the “first real-world evidence of vaccine effectiveness” against the variant first identified in India.

Conducted between April and May, the research found that the Pfizer-BioNTech vaccine was 88% effective against symptomatic disease from the B.1.617.2 Covid variant, a sub-type of a variant that emerged in India last fall since spread to Europe, two weeks after the second dose. The vaccine was 93% effective two weeks after the double dose against the B.1.1.7 variant, first discovered in the U.K. last fall.

Meanwhile, two doses of the AstraZeneca vaccine were 60% effective against symptomatic disease from the B.1.617.2 variant from India, compared to 66% effective against the variant from the U.K.

“Vaccine effectiveness against symptomatic disease from the B.1.617.2 variant is similar after two doses compared to the B.1.1.7 (Kent) variant dominant in the U.K., and we expect to see even higher levels of effectiveness against hospitalization and death,” the study authors wrote. The results were published Saturday as a pre-print, and the study has not yet been peer-reviewed.

PHE said the difference in effectiveness between the vaccines after two doses “may be explained by the fact that rollout of second doses of AstraZeneca was later than for the Pfizer-BioNTech vaccine, and other data on antibody profiles show it takes longer to reach maximum effectiveness with the AstraZeneca vaccine.”

However, both vaccines were 33% effective against symptomatic disease from B.1.617.2 three weeks after the first dose. In the same time frame, they were 50% effective against the B.1.1.7 variant.

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