The vaccine from Pfizer / BioNtech laboratories is more effective in fighting cases linked to the delta variant of the coronavirus than the one developed by Oxford / AstraZeneca, but its efficacy disappears more quickly, a British study concluded.
Researchers at the University of Oxford studied samples from about 700,000 people between December 2020 and August 2021.
And this analysis established that for infections with a high viral load, a person who received their second dose of Pfizer a month earlier was 90% more protected against the delta variant than an unvaccinated person. This percentage drops to 85% two months later and 78% three months later.
People who received the two AstraZeneca injections are 67% protected one month later, 65% two months later, and 61% three months later. After four or five months, the level of protection offered by the two vaccines is similar, according to this study, which is still to be validated.
These figures represent a decline in the effectiveness of Pfizer’s vaccine, explained Dr. Koen Pouwels, who participated in the study, while for AstraZeneca “the differences (between one month and another) are minimal, that is, there may not be any change in protection “.
The expert 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 the news that several countries, including the United Kingdom, plan to launch a campaign to inject a third dose of the vaccine.