AstraZeneca COVID-19 vaccine is as effective as Pfizer in fighting Delta, major study shows

AstraZeneca's reputation as a second-best option has been proved wrong.

AstraZeneca's reputation as a second-best option has been proved wrong. Photo: AAP

The AstraZeneca vaccine has suffered with a reputation as a second-rate jab – and many people have apparently been waiting around for the Pfizer vaccine to become available, thinking it would provide superior protection.

Well, that assumption was wrong.

Yet another study, the largest of its kind, has shown that over time, two doses of Pfizer and two doses of AstraZeneca are actually on par – in terms of preventing serious illness and hospitalisation.

If you were to look at the performance of the two vaccines as a horse race, Pfizer comes out of the gate stronger. But over four to five months, its performance falls back – and runs roughly equal to AstraZeneca.

“Two doses of Pfizer-BioNTech have greater initial effectiveness against new COVID-19 infections, but this declines faster compared with two doses of Oxford-AstraZeneca,” researchers at Oxford University said.

According to a BBC report, the Pfizer-BioNTech vaccine had 93 per cent effectiveness against symptomatic infection two weeks after the second dose, compared with Oxford-AstraZeneca’s 71 per cent.

The new study looked at data between December 2020 and August 2021 from the COVID-19 Infection Survey.

Swab tests from more than 700,000 participants were analysed from before and after May 17 2021, when Delta became the main variant in the UK.

Pfizer comes on strong

The study found that both vaccines were less effective against the Delta than the Alpha strain – but two doses from either Pfizer or AstraZeneca were still the best protection against illness caused by the Delta strain.

According to a report in Ireland’s The Journal, analysis revealed that “for infections with a high viral load, protection a month after the second Pfizer dose was 90 per cent greater than an unvaccinated individual, reducing to 85 per cent after two months and 78 per cent after three.”

Pfizer’s effectiveness kept falling while AstraZeneca’s effectiveness appears to remain stable.

The takeaway: if you’ve delayed getting yourself jabbed because you thought Pfizer did a better job, all you’ve achieved is wasting valuable time.

Last month, Israel’s health ministry reported that the efficacy of Pfizer’s vaccine had dropped from more than 90 per cent to about 64 per cent following the spread of the Delta variant.

Pfizer and BioNTech said the data suggested that a third booster shot appeared necessary for heightened protection.

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