RIO DE JANEIRO, BRAZIL – The Pfizer/BioNtech vaccine is more effective in fighting Delta coronavirus cases than Oxford/AstraZeneca’s, but its efficacy fades faster, a British study says.
The study established that for high viral load infections, a Pfizer second-dose recipient was 90% more protected against the Delta variant one month before than an unvaccinated individual. The percentage drops to 85% two months later, and 78% three months later.
In parallel, people administered two AstraZeneca doses are 67% protected one month later, 65% two months later, and 61% three months later.
After four or five months the protection level offered by the two vaccines is similar, according to the study, which is yet to be peer reviewed.
These data “represent a regression” in the efficacy of Pfizer’s vaccine, explained Dr. Koen Pouwels, who took part in the study, while for AstraZeneca’s immunizer, “the differences (between one month and the next) are minimal, meaning there may be no change in protection.”
He insisted that, “despite the slight drop in the level of protection, the overall efficacy (of the two vaccines) remains very high.”
The study coincides with news that several countries, including the UK, are planning to start a campaign for a third booster dose of the Covid-19 vaccine.