The most vaccinated country in the world is experiencing a spike in coronavirus cases – but so far, the Pfizer vaccine has proven to be effective in preventing serious illness.
It was reported in late June that Israel was seeing an increase in new coronavirus cases.
A deeper look at the numbers revealed that roughly 70 per cent of new infections were linked to the highly transmissible Delta variant and 30 per cent were recorded in Israel's vaccinated population.
So concerned was Israel's leadership that authorities urged children between the ages of 12 and 15 to get vaccinated against Covid-19.
On Tuesday, Israel's Health Ministry revealed that vaccine effectiveness among those who have received two shots of the Pfizer/BioNTech jab dropped to as low as 64 per cent.
That means almost one in every three people who were fully vaccinated between June 6 and early July were still able to be infected with coronavirus.
However, the ministry said the Pfizer jab was so far still 93 per cent effective in preventing hospitalisation and serious illness.
The rise in cases also coincides with the ending of social distancing rules in the nation in early June, which is when the Delta variant began to take hold.
In other words, it appears that while the vaccination can't prevent the spread of infection entirely, it can greatly reduce the chances of an infected individual falling seriously ill.
Israel news service Haaretz reports that Israeli data published in March showed that two doses of the vaccine "had 99 per cent efficacy in preventing symptomatic Covid-19 and 91.2 per cent in preventing infection".
Ran Balicer, chairman of Israel's national expert panel on Covid-19, responded to the new data by stressing it was "too early to precisely assess vaccine effectiveness against the variant" first identified in India in April that is surging across the globe.
That is partly due to the overall low number of cases among fully vaccinated Israelis, and because exposure to the virus and the likelihood of being tested are not evenly distributed across the population, further complicating efforts to reach conclusions about the data.
Balicer, also the chief innovation officer at Clalit, Israel's largest health maintenance organisation, told AFP that the Delta variant's emergence as the "dominant strain" in the country has led to a "massive shift in the transmission dynamic".
Israel's vaccine rollout, which began in December, was one of the world's fastest, making the Jewish state a closely watched case study on whether mass inoculation offers a path out of the pandemic.
Vaccinations had brought transmission down to about five local new cases per day, but that figure has risen to around 300 in recent days, with the Delta variant raging.
About half of the daily cases are among children, and half are among mostly vaccinated adults.
"To some extent that could be expected since 85 per cent of Israeli adults are vaccinated," Balicer said.
"But the rates in which we see these breakthrough cases make some believe they extend beyond that expected point and suggest some decrease in vaccine effectiveness against mild illness — but not severe illness — is likely."
The number of severe cases among vaccinated Israelis has risen in recent days from roughly one every two days up to five cases per day, Balicer said.
He said it was also too early to draw conclusions about the vaccine's effectiveness against serious illness caused by the Delta variant.
But, he added, experts "remain hopeful that the vaccine effectiveness against serious illness will remain as high as it was for the Alpha strain" identified for the first time in Britain in December.
Israeli Prime Minister Naftali Bennett warned on Sunday that "with the Delta variant running amok" Israel may have to reintroduce certain restrictions that were lifted last month.
Balicer said it was unlikely Israel could contain rising cases without restrictions being reimposed, but voiced hope they would be mild and that Israel's "vaccine wall" of inoculated citizens will help reduce further spread.
"It is encouraging that we still maintain zero deaths for the last twelve days," he said.
On June 15, Israel lifted its requirement to wear face masks in enclosed public places – one of the last measures in force to fight the country's outbreak.
The country has recorded over 840,000 novel coronavirus cases, including 6429 deaths.