A new Israeli study suggests that the South African Covid variant can “break through” the Pfizer vaccine.

Tel Aviv University researchers studied 400 people who tested positive for Covid-19 after being vaccinated at least two weeks previously and the same number of unvaccinated people with the virus.

The South African variant accounted for around 1 per cent of the cases studied.

But among patients who had received two doses of the vaccine, the variant's prevalence was eight times higher than among those unvaccinated - 5.4 per cent compared to 0.7 per cent.

“We found a disproportionately higher rate of the South African variant among people vaccinated with a second dose, compared to the unvaccinated group,” said the university’s Adi Stern.

“This means that the South African variant is able, to some extent, to break through the vaccine’s protection.”

The researchers advised caution given the small number of people in the study with the South African variant, which is rare in Israel. Pfizer said earlier this month that its jab is around 91 per cent effective at preventing Covid.