According to a study by Oxford University researchers, the effectiveness of the Pfizer / Bioentech vaccine is declining faster than the Oxford-Astrogeneka against the delta variant.
Before reaching this conclusion, British scientists who developed one of the two series studied samples taken from more than 700,000 people between December 2020 and August 2021, according to Agency France-Press (AFP).
One month later, a person receiving a second dose of the vaccine developed by Pfizer Laboratory for infections with a high viral load was protected from 90% more corona virus delta variants than the unvaccinated person.
78% efficiency for Pfizer after three months
After two months, this number drops to 85%, and then after three months to 78%. 67% of individuals who received two injections of the AstraZeneca vaccine were protected after one month, 65% after two months, and 61% after three months.
After four to five months, the level of protection of these two vaccines is similar, the authors of this study noted, which, so far, has not been verified by colleagues.
These figures “actually indicate a decline” in the effectiveness of Pfizer’s vaccine, said Dr. Coyne Powell, who participated in the study, which was published on Thursday, August 19th.
The effectiveness of both vaccines is “very high”.
Regarding the AstraZeneca vaccine, he said, “Differences (from month to month) are likely due to the fact that there can be no change in safety”.
However, despite “these small drops in protection”, the overall performance (two serums) is very high, the doctor said.
He stressed that the researchers had studied the overall safety and did not study the severity of the forms and the level of protection against hospitalizations, “two very important data for evaluating the effectiveness of vaccines.