Sari Roos, a trained nurse, prepares a dose of Pfizer / BioNTech vaccine against coronavirus disease (COVID-19) to teach her air bubble technique at Laakso Hospital in Helsinki, Finland, on 11 March 2021. Photograph taken March 11, 2021. REUTERS / Essi Lehto
The coronavirus variant discovered in South Africa may open up the protection provided by Pfizer Inc. and BioNTech’s COVID-19 vaccine to some extent, according to a real-world data study conducted in Israel. However, the prevalence of the variant in Israel is very low and the vaccine remains very effective.
The study was published on the medRxiv prepress site on April 9 and has not been peer-reviewed. Nearly 400 people who tested positive for COVID-19 after receiving one or two doses of the vaccine were compared with the same number of patients not vaccinated with the disease.
It combined age and gender, among other characteristics.
The South African variant, B.1.351, was found to account for approximately 1% of all COVID-19 cases in all people studied, according to the Tel Aviv University study and the largest healthcare provider. of Israel, Clalit.
But among patients who had received two doses of the vaccine, the prevalence rate of the variant was eight times higher than that of the unvaccinated: 5.4% versus 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 Britain that has come to include almost all cases of COVID-19 in Israel, said the researchers.
The researchers said the study was not intended to assess the overall effectiveness of the vaccine against any variant, as they only looked at people who had already tested positive for COVID-19, not the overall infection rates.
Real-world Israeli studies on the overall effectiveness of the vaccine, including those of Clalit, have shown that Pfizer’s shot is more than 90% 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 break protection. of the vaccine, “Tel. Adi Stern of Aviv University.
In an update of the study published on April 16, the researchers noted that within the group of people who received two doses, comprising eight people, all B.1,351 infections occurred within a week to 13 days after the second shot. None of them tested positive for 14 days or more after the second dose.
“This may imply that there is a brief window of susceptibility to B.1.351 infection limited to the two weeks immediately following the second dose, but we cannot be sure that this is the case,” said Ran Balicer of Stern and Clalit, in an email. on Reuters on Sunday.
The researchers warned, however, that the study had only a small sample size of people infected with the South African variant due to its rarity in Israel.
“The incidence of B.1.351 in Israel is still low and the effectiveness of the vaccine remains high among those completely 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 trials that included participants inoculated for up to six months.
They have been testing a third dose of their shot as reinforcement and have said they could modify the shot to specifically address new variants if necessary.
Regarding the South African variant, they said that among a group of 800 student volunteers in South Africa, where B.1.351 is widespread, there were nine cases of COVID-19, which occurred among participants who obtained the placebo. Of these nine cases, six were from people infected with the South African variant. Read more
Some previous studies have indicated that the Pfizer / BioNTech trait was less potent against variant B.1.351 than against other coronavirus variants, but still offered a powerful defense.
While the results of the study may cause concern, the low prevalence of the South African strain was encouraging, according to Stern.
“Even if the South African variant breaks vaccine protection, it has not spread widely to the population,” Stern said, adding that the British variant could “block” the spread of the South strain. African.
More than half of Israel’s 9.3 million people have received doses of Pfizer. Israel has largely reopened its economy in recent weeks, while the pandemic appears to be receding with a sharp drop in infections and hospitalizations.
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