According to a recent study published on Thursday, the effectiveness of the Pfizer-BioNTech vaccination against Covid-19 falls faster than that of the AstraZeneca vaccine.

“Two doses of Pfizer-BioNTech had stronger initial efficacy against new COVID-19 infections, but this diminishes faster than two doses of Oxford-AstraZeneca,” Oxford University researchers concluded.

The study, which has not been peer-reviewed, is based on the findings of a survey conducted by the Office for National Statistics in the United Kingdom, which used PCR tests on randomly selected houses from December last year to this month.

According to the university’s Nuffield Department of Medicine, “the dynamics of immunity following second doses differed dramatically” between Pfizer and AstraZeneca.

When looking at a period of several months following full immunization, Pfizer had “higher initial effectiveness,” but “faster reductions in protection against high viral burden and clinical infection,” even though rates remained low for both jabs.

“The results suggest that the effectiveness of these two vaccines would be equivalent after four to five months,” the researchers said, adding that long-term impacts must be investigated.

The findings of the study are being released as Israel prepares to administer booster shots after giving 58 percent of the population two doses of the Pfizer vaccine.

Following worries about the Pfizer and Moderna vaccines’ diminishing efficiency, the US is planning to issue booster injections to raise antibody levels.

The Oxford study also discovered that people who had already been infected with the virus had better protection.