Scientists working on a Tel Aviv University study examined 400 people who had tested positive for coronavirus at least 14 days after taking one or two doses of the jab - and 400 people who had tested positive but hadn’t been vaccinated.
The variant was eight times more prevalent in those who had two jabs than none.
It was detected in 5.4 per cent of people with two doses - but 0.7 per cent of people without any.
Scientists said their results suggested the South African variant is more resistant to vaccines.
Tel Aviv University researcher Adi Stern told ABC News: “We found a disproportionately higher rate of the South African variant among people vaccinated with a second dose, compared to the unvaccinated group.”
However, scientists stressed that of the 800 people examined, the South African Covid variant was identified in just 1 per cent of positive tests due to the rarity of the variant cases in Israel.
The SA variant is thought to be at least 60 per cent more transmissible than the original and more infectious than the Kent variant.
Last week the government said people under 30 will be offered the Moderna and Pfizer vaccine as alternatives to the AstraZeneca jab in the UK.
The medicines regulator said there was a possible link between the jab and “extremely rare” blood clots.
A review by the European Medicines Agency (EMA) concluded on Wednesday that “unusual blood clots with low blood platelets should be listed as very rare side effects” of the Oxford/AstraZeneca vaccine.
On Sunday, NHS England said a total of 33,248,869 Covid-19 vaccinations took place in England between December 8 and April 10, including first and second doses.
They added that 27,070,991 were the first dose of a vaccine, a rise of 74,055 on the previous day, while 6,177,878 were a second dose, an increase of 437,442.