Nurse Sari Roos is preparing a dose of Pfizer / BioNTech coronavirus vaccine (COVID-19) to learn her air bubble technique at Laakso Hospital in Helsinki, Finland, March 11, 2021. Picture taken March 11, 2021. REUTERS / Essi Lehto
The coronavirus variant discovered in South Africa may go through the protection provided by Pfizer Inc. and BioNTech’s COVID-19 vaccine to some extent, a study of real-world data from Israel found. However, the prevalence of the variant in Israel is very low and the vaccine remains extremely effective.
The study was launched on the pre-print site medRxiv on April 9 and was not reviewed by colleagues. He compared nearly 400 people who tested positive for COVID-19 after receiving one or two doses of the vaccine to the same number of unvaccinated patients.
It matched age and gender, among other features.
The South African variant, B.1.351, was found to account for approximately 1% of all COVID-19 cases in all subjects, according to a study by Tel Aviv University and Israel’s largest healthcare provider, Clalit.
But among patients who received two doses of vaccine, the prevalence rate of the variant was eight times higher than those who were not vaccinated – 5.4% compared to 0.7%.
This suggests that the vaccine is less effective against the South African variant compared to the original coronavirus and a variant first identified in the UK, which has come to cover almost all cases of COVID-19 in Israel, the researchers said. .
The researchers said the study was not intended to assess the overall effectiveness of the vaccine compared to any variant, as it only looked at people who had already tested positive for COVID-19, not the overall infection rates.
Separate real-world Israeli studies on the overall effectiveness of the vaccine, including by Clalit, showed that Pfizer was 90% more effective. L1N2KU3L6
“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 go through vaccine protection.” , said Tel. Aviv University, Adi Stern.
In an update of the study published on April 16, the researchers noted that in the group of people who received two doses, which included eight people, all B.1.351 infections appeared within a week to 13 days after the second blow. None of them tested positive for it 14 days or more after the second dose.
“This may imply that there is a short window of susceptibility to B.1.351 infection limited to two weeks immediately after the second dose – but we cannot be sure that this is indeed the case,” said Ran Balicer of Stern and Clalit, in an email. on Sunday at Reuters.
The researchers warned, however, that the study had only a small sample of people infected with the South African variant because of its rarity in Israel.
“The incidence of B.1.351 in Israel so far remains low and the effectiveness of the vaccine remains high among those fully vaccinated,” the study said.
Pfizer (PFE.N) declined to comment on the Israeli study. Pfizer and BioNTech (22UAy.DE) said on April 1 that their vaccine was about 91% effective in preventing COVID-19, citing updated data from studies that included inoculated participants for up to six months.
They tested the third dose of their shot as a booster and said they could modify the shot to specifically address new variants if necessary.
Regarding the South African version, they said that among a group of 800 studied volunteers from South Africa, where B.1.351 is widespread, there were nine cases of COVID-19, all of which occurred among participants who they received a placebo. Of the nine cases, six were among those infected with the South African variant. Read more
Some previous studies have shown that the Pfizer / BioNTech shot was less potent against variant B.1.351 than against other variants of coronavirus, but still provided a strong defense.
While the results of the study may cause concern, the low prevalence of the South African strain has been encouraging, according to Stern.
“Even though the South African version penetrates the vaccine protection, it has not spread widely among the population,” Stern said, adding that the British version could “block” the spread of the South African strain.
More than half of Israel’s 9.3 million people received both doses of Pfizer. Israel has largely reopened its economy in recent weeks, while the pandemic appears to be declining, with a sharp decline in infections and hospitalizations.
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