Two doses of Pfizer were 88 percent effective in preventing the Delta variant, while two doses of AstraZeneca were 67 percent effective.
Two doses of Pfizer or AstraZeneca’s COVID-19 vaccine are almost the same effective against the highly transmissible Delta coronavirus variant as it is against the previously dominant Alpha variant, according to a new study.
Research published in the New England Journal of Medicine on Wednesday showed that the vaccines are very effective against the Delta variant, now the dominant strain worldwide, provided someone gets two shots.
The study confirms the main findings of Public Health England (PHE) in May on the efficacy of COVID-19 vaccines made by Pfizer-BioNTech and Oxford-AstraZeneca based on actual data.
Wednesday’s study found that Pfizer was 88 percent effective in preventing symptomatic diseases of the Delta variant with both doses, compared to 93.7 percent versus the Alpha variant, generally the same as previously reported.
Two shots of AstraZeneca vaccine was 67 percent effective against the Delta variant, compared to 60 percent originally reported, and 74.5 percent effective against the Alpha variant, compared to an original estimate of 66 percent efficiency.
“Only modest differences in vaccine efficacy were observed with the Delta variant compared to the Alpha variant after receiving two doses of vaccinations,” Public Health England researchers wrote.
According to data from Israel, Pfizer’s shot is less effective against symptomatic diseases, although the protection against serious diseases is still high.
PHE said earlier that the first dose of any vaccine was approximately 33 percent effective against Delta variant symptomatic diseases.
Other vaccines are also useful
The full study, published Wednesday, found that one dose of Pfizer’s shot was 36 percent effective and one dose of AstraZeneca’s vaccine about 30 percent effective.
“Our finding of reduced efficacy after the first dose would support the efforts to maximize the uptake of two-dose vaccines among vulnerable groups in the context of the distribution of the Delta variant,” the study authors said.
Recently, researchers from Beth Israel Deaconess Medical Center in the US city of Boston also said that the antibody response of the one-dose Johnson & Johnson vaccine in a laboratory setting worked well against Delta and that the immune response lasted about eight months.
In June, manufacturers of Russia’s Sputnik vaccine also said it is about 90 percent effective against the highly contagious Delta variant.
The shot, which Russia actively marketed abroad, was previously found by researchers nearly 92 percent effective against the original coronavirus strain.
According to the Russian state-controlled RIA, reports Denis Logunov, the deputy director of the Gamaleya Institute in Moscow, which developed Sputnik.
However, the Sputnik vaccine has caused some controversy as it was introduced to the public even before a full trial was completed. It is still awaiting approval from the World Health Organization.