Pfizer, AstraZeneca jabs less effective against Delta strain after three months – study
A new study in the UK has found out that Pfizer and AstraZeneca coronavirus vaccines are less effective against the Delta variant three months after inoculation.
From the study, after 90 days of two doses of the vaccines, the efficacy of Pfizer-BioNTech dropped to 75 per cent from 93 per cent two weeks after receiving the shot against Covid-19.
Oxford-AstraZeneca’s efficiency dropped to 61 per cent after three months from 71 per cent two weeks after the second dose.
The drop in effectiveness was also more visible for those aged 35 years and above.
However, the study highlighted both vaccines still staved off the majority of COVID-19 variants.
“With Delta, Pfizer-BioNTech and Oxford/AstraZeneca vaccines still offer good protection against new infections,” the study said.
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Sarah Walker, an Oxford professor of medical statistics and chief investigator for the survey said “both of these vaccines, at two doses, are still doing really well against Delta… When you start very, very high, you’ve got a long way to go.”
The study was produced by the University of Oxford and the Office for National Statistics and it analyzed the periods before and after the Delta variant became prevalent.
Between December 2020 and May, it analyzed more than 2.5 million swabs from 380,000 adults. Between May 17 and August 1, it analyzed the test results of 360,000 people.
From the analysis, neither vaccine was found to be as effective against the Alpha variant, which was first identified in the UK in September last year.
Researchers also said there was insufficient data for Moderna, but said: “A single dose of the Moderna vaccine has similar or greater effectiveness against the Delta variant as single doses of the other vaccines.”
