Vaccine blow: Pfizer jab effectiveness declines faster than AstraZeneca – new major study

Man jailed for pretending to administer a fake Covid-19 vaccine

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Oxford University scientists say levels of the virus could be just as high in people who get COVID-19 despite having both jabs as in those who have not been vaccinated. The study, involving more than 700,000 randomly selected people, suggested the Delta variant could mean “herd immunity is more challenging”. But scientists noted the protection against illness and death is still high.

Dr Koen Pouwels, one of the lead researchers of the study, said: “The vaccines are better at preventing severe disease and are less effective at preventing transmission.

“The fact that you see more viral load (with the Delta variant) hints towards herd immunity being more challenging.”

The vaccines were highly effective at stopping infections when the Alpha variant was rampant in Britain earlier this year.

But since then, the Delta variant has proved more difficult to block, according to the results.

The researchers found that protection from the Pfizer and AstraZeneca vaccines weakens within three months.

Professor Sarah Walker, Chief Investigator for the Survey, said: “We don’t yet know how much transmission can happen from people who get COVID-19 after being vaccinated – for example, they may have high levels of virus for shorter periods of time.

“But the fact that they can have high levels of the virus suggests that people who aren’t yet vaccinated may not be as protected from the Delta variant as we hoped.”

Scientists broke down the immunity over time.

They say that two weeks after getting the second dose, the Pfizer jab was 85 percent effective at preventing PCR-confirmed infection, considerably better than the AstraZeneca shot, which was 68 percent effective.

But the protection of the Pfizer jab is said to have declined more rapidly.

Three months after the second dose it prevented 75 percent of infections, compared to 61 percent protection with the AstraZeneca jab.

Professor Walker added: “These two vaccines look like they are working in very different ways.

“But it’s the rates of hospitalisations and deaths that we really need to keep our eye on.”

The study has been published as a pre-print and has not been peer-reviewed yet.

Dr Alexander Edwards, Associate Professor in Biomedical Technology at the University of Reading, said the results were “compelling”.

He added: “Overall this study is excellent as it shows that although Delta is better at infecting vaccinated people than previous variants, the vaccines still work remarkably well.

“There are subtle differences between different vaccine types, and some changes over time, but they all work brilliantly.

“It does remain vital to remember that even if double jabbed, you can still get infected and pass the virus on.”

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