(April 10 updates with additional information from researchers)
By Maayan Lubell
JERUSALEM, April 18 (Reuters) – The coronavirus variant discovered in South Africa could, to some extent, break the protection offered by Pfizer Inc and the COVID-19 vaccine from BioNTech, an actual data study in Israel find. However, the incidence of the variant in Israel is very low and the vaccine remains very effective.
The study was launched on April 9 on the medRxiv pre-print website and was not reviewed by peers. This compares almost 400 people who tested positive for COVID-19, after receiving one or two doses of the vaccine, against the same number of unvaccinated patients with the disease.
It fits under age and gender, among other characteristics.
According to the study by the University of Tel Aviv and Israel’s largest healthcare provider, Clalit, the South African variant, B.1.351, was found to account for approximately 1% of all COVID-19 cases for all the people studied.
However, among patients who received two doses of the vaccine, the incidence of the variant was eight times higher than that which was 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 contains almost all COVID-19 cases in Israel, the researchers said. said.
The researchers said the study was not intended to assess overall vaccine efficacy against any variant, as it only looked at people who had already tested positive for COVID-19, not against the overall infection rates.
Separate actual Israeli studies on the overall efficacy of the vaccine, including by Clalit, have shown that the Pfizer shot is more than 90% effective.
“We found an excessively higher percentage of the South African variant among people who were vaccinated with a second dose, compared to the group who were not vaccinated. This means that the South African variant has to some extent the protection of the vaccine could break through, “said Tel. Aviv University’s Adi Stern.
In an update of the study published on April 16, the researchers noted that within the group of people who received two doses, consisting of eight people, all B.1.351 infections within a week to 13 days after the second shot took place. None of them tested positive for it 14 days or longer after the second dose.
“This may imply that there is a brief window of susceptibility to B.1.351 infection that is limited to the immediate two weeks after the second dose – but we can not trust that this is indeed the case,” said Ran Balicer of Stern and Clalit said in an email. to Reuters Sunday.
However, the researchers warn that the study had only a small sample size of people infected with the South African variant, because it is rare in Israel.
“The prevalence of B.1.351 in Israel so far remains low and the effectiveness of the vaccine remains high among those who have been fully vaccinated,” the study said.
Pfizer declined to comment on the Israeli study. Pfizer and BioNTech said on April 1 that their vaccine was approximately 91% effective in preventing COVID-19, citing updated trial data that included participants vaccinated for up to six months.
They tested a third dose of their shot as an enhancer, and said they could change the shot to specifically address new variants if needed.
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 had the got placebo. Of the nine cases, six were infected with the South African variant.
Some previous studies have indicated that the Pfizer / BioNTech shot was less potent against the B.1.351 variant than against other variants of the coronavirus, yet offered a powerful defense.
Although the results of the study may be of concern, the low incidence of the South African tribe was encouraging, according to Stern.
“Although the South African variant did break through the protection of the vaccine, it did not spread widely among the population,” Stern said, adding that the British variant could possibly “block” the spread of the South African strain.
More than half of Israel’s 9.3 million population have both received Pfizer doses. Israel has largely reopened its economy in recent weeks, while the pandemic appears to be declining with a sharp decline in infections and hospitalizations. (Reporting by Maayan Lubell; Edited by Pravin Char, Frances Kerry and Daniel Wallis)