Training nurse Sari Roos prepares a dose of Pfizer / BioNTech vaccine against coronavirus disease (COVID-19) to learn her air bubble technique at Laakso Hospital in Helsinki, Finland, March 11, 2021. Photo taken March 11, 2021. REUTERS / Essi Lehto
The coronavirus variant discovered in South Africa could, to some extent, break the protection afforded by Pfizer Inc and BioNTech’s COVID-19 vaccine, a real-world data study in Israel found. However, the prevalence of the variant in Israel is very low and the vaccine remains very effective.
The study was published April 9 on medRxiv’s pre-print site and has not been peer-reviewed. It compared nearly 400 people who tested positive for COVID-19, after receiving one or two doses of the vaccine, with the same number of unvaccinated patients with the disease.
Among other things, it corresponded to age and gender.
According to the study from Tel Aviv University and Israel’s largest healthcare provider, Clalit, the South African variant, B.1.351, was found to account for about 1% of all COVID-19 cases in all people studied.
But among patients who received two doses of the vaccine, the prevalence of the variant was eight times higher than those who were not vaccinated – 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 included nearly all COVID-19 cases in Israel, the researchers said.
The researchers said the study was not intended to assess the overall effectiveness of the vaccine against 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, have shown the Pfizer injection to be over 90% effective. L1N2KU3L6
“We found a disproportionately higher percentage of the South African variant among people vaccinated with a second dose, compared to the unvaccinated group. This means that the South African variant may, to some extent, break the protection of the vaccine. “said Tel. Adi Stern from Aviv University.
In an update of the study posted April 16, the researchers noted that within the group of people who received two doses, consisting of eight people, all B.1.351 infections occurred within a week to 13 days after the second injection . None of them tested positive for it 14 days or more after the second dose.
“This may mean that there is a short period of susceptibility to B.1.351 infection, limited to the immediate two weeks 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. to Reuters on Sundays.
However, the researchers cautioned that the study only had a small sample of people infected with the South African variant due to its rarity in Israel.
“The incidence of B.1.351 in Israel to date remains low and vaccine effectiveness remains high among those who have been 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 study data with participants vaccinated for up to six months.
They tested a third dose of their shot as a booster and said they can adjust the shot as needed to specifically target new variants.
Regarding the South African variant, they said that among a group of 800 study volunteers in South Africa, where B.1.351 is widespread, there were nine cases of COVID-19, all of which occurred among participants who received the placebo. Of those nine cases, six were among individuals infected with the South African variant. read more
Some previous studies have shown that the Pfizer / BioNTech shot was less powerful against the B.1.351 variant than against other variants of the coronavirus, but still provided a powerful defense.
While the results of the study may be concerning, the low prevalence of the South African species was encouraging, according to Stern.
“Even if the South African variant breaks through the vaccine’s protection, it has not spread widely among the population,” said Stern, adding that the British variant could “block” the spread of the South African species.
More than half of Israel’s 9.3 million residents have received both doses of Pfizer. Israel has largely reopened its economy in recent weeks, while the pandemic appears to be easing with a sharp drop in infections and hospital admissions.
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