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Although earlier less effective, the Oxford-AstraZeneca jab provides the same high protection as the Pfizer-BioNTech after four to five months, the principal study of its kind denotes.
However, the jabs are not more effective than against the Alpha variant, responsible for most UK infections last winter.
The data is insufficient for Moderna. However, researchers believe it “almost certainly at least as good as the others”.
They analysed two and a half million tests from 743,526 participants in the UK’s Covid-19 household-infection survey – run by Oxford University and the Office for National Statistics.
The Pfizer-BioNTech vaccine provided 93% effectiveness against symptomatic infection two weeks after the second dose compared to Oxford-AstraZeneca’s 71%.
Over time, though, Pfizer-BioNTech’s effectiveness reduced while the Oxford-AstraZeneca’s mainly remained the same.
However, there was no reason for alarm, Prof Sarah Walker, at the University of Oxford, stated because “when you start very very high, you’ve got a long way to go”.
“The World Health Organization set the bar at 50% and we’re way above that,” she added.”Both of these vaccines are still doing very well against Delta.”
Research also brings out the below points:· People who have had Covid-19 gain even more antibodies after both jabs
- The time between first and second doses does not impact the vaccines’ effectiveness
- Younger people get more protection from vaccination than older
The study also resounds the previous research showing that fully vaccinated people who become infected with the Delta variant have similar virus levels to those unvaccinated. With the Alpha variant, however, their viral loads were much lower.
”We don’t yet know how much transmission can happen from people who get Covid-19 after being vaccinated,” Prof Walker mentioned. “For example, they may have high levels of virus for shorter periods. They have the potential to transmit as much. 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. It means it is essential for as many people as possible to get vaccinated – both in the UK and worldwide.”
