A variant of the coronavirus in South Africa is better at "breaking through" the protection of Pfizer / BioNTech vaccines than other forms of the virus, Israeli experts said on Sunday.
However, one of the authors told AFP that while the study showed the variant to be relatively successful in infecting vaccinated people, it did not provide any data on whether it could generate serious diseases among the vaccines.
A study by Tel Aviv University and Clalit Health Services, Israel's largest healthcare provider, compared 400 unvaccinated people infected with COVID-19 with 400 partially or fully vaccinated people who also had the virus.
The South African version accounts for less than one percent of coronavirus cases in Israel, according to a study published as a draft on Saturday and currently being peer-reviewed.
But, among the 150 people in the study who were fully vaccinated and COVID-19, "the prevalence (of the South African variant) was eight times higher than that of the unvaccinated (individuals)," the study said.
"This means that the Pfizer-BioNTech vaccine, while highly protective, probably does not provide the same level of protection against the South African (B. 1.351) variant of the coronavirus," the study said.
"To some extent, the South African variant is able to break through the protection of the vaccine," says Professor Adi Stern from the School of Biomedicine and Cancer Research at Tel Aviv University, one of the authors of the study.
Stern told AFP Sunday the study did not assess whether fully vaccinated Israelis with the South African variant-eight people in total-had developed serious illnesses.
"Since we found a very small number of vaccines infected with B. 1.351, it is statistically meaningless to report disease outcomes," he said.
Two studies published in February in the New England Journal of Medicine, conducted by major vaccine manufacturers Pfizer/BioNTech and Moderna, found that the presence of antibodies after vaccination was less pronounced in people exposed to the South African variant, indicating reduced protection.
The Israeli study was the first real assessment of the ability of the South African variant to circumvent the vaccine.
As a result of the Israeli vaccination campaign, 5.3 million people received the first dose, while 4.9 million people, or 53 percent of the population, fired two shots.
An earlier Clalit study of 1.2 million Israelis found that the Pfizer / BioNTech strike gave 94 percent protection against COVID-19.
Since the successful introduction of vaccination, Israel has relaxed many of its restrictions, but various measures are still being taken, including the wearing of masks and the "green passport" system, which provides access to certain places only for the vaccinated.
Ran Baliser of Clalit, one of the study's authors, told AFP the results could help inform states on how best to ease restrictions.
Balicer said vaccinations, as well as mask-wearing and other safety measures still likely helped limit the spread of the South African variant, despite its apparent ability to break through Pfizer / BioNTech vaccines.
A combination of all these factors, " most likely... preventing the spread of virus strains, including South African ones, in Israel, he said.
"As we develop non-ampere measures, we need to do this gradually, so as not to cross the threshold that would allow these options to spread."