Pfizer Vaccine May Not Fully Protect Against South African Variant

The real-world data study in Israel had a small sample size but provided interesting results that are worth looking into.
Derya Ozdemir

The Pfizer/BioNTech’s COVID-19 vaccine may not provide as much protection against the South African variant, B.1.351, according to a preliminary study by the researchers at Tel Aviv University and Israel’s largest health care organization, Clalit.

While it should be noted that the research is yet to be peer-reviewed, the findings suggest that the B.1.351 variant can penetrate the protection offered by the two doses of the vaccine.

'Break through' the protection of the vaccine

The researchers studied more than 400 people who tested positive for COVID-19 at least two weeks later after they received one or two doses of the Pfizer vaccine. They compared these people to the same number of unvaccinated and infected patients, matching characteristics like age and gender.

Those infected with the South African variant made up only about 1 percent of the people who took part in the study because of the variant's rarity in Israel. The researchers saw that the prevalence rate of the variant was eight times higher than those who were unvaccinated. Among patients who had received two doses of the vaccine percent, the variant’s prevalence rate was eight times higher than those unvaccinated-- 5.4 percent versus 0.7 percent.

This suggests that the South African variant is better able to "break through" the protection of Pfizer's vaccine than the original strain, the researchers wrote in the study, possibly providing less protection.

“We found a disproportionately higher rate of the South African variant among people vaccinated with a second dose, compared to the unvaccinated group. This means that the South African variant is able, to some extent, to break through the vaccine’s protection,” said Tel Aviv University’s Adi Stern to Reuters.

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It should be highlighted that the study only had a small sample size and it isn't enough to comment on the vaccine's general effectiveness. The researchers also stated that the research only focused on people who had already tested positive for COVID-19, not on overall infection rates.

Pfizer/BioNTech announced on April 1 that the ongoing Phase 3 clinical trial of their coronavirus vaccine has confirmed its protection lasts at least six months after the second dose and also been found to be effective against the B.1.351 variant in a relatively small study of 800 participants. The vaccine was found to be 91 percent effective at preventing COVID-19. 

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