Dr Nachman Ash told Israel’s Army Radio: “Many people have been infected between the first and second injections of the vaccine.” The coronavirus vaccine trains the immune system to fight the virus. It can take up to 10 days or more for a person’s immunity to kick in.
Currently, it is not confirmed yet whether the vaccine stops a patient from catching and spreading the virus.
It is only known that the jab can stop people from getting ill.
In the US, at least one American has been infected with COVID-19 after his first dose of the Pfizer jab, according to reports.
Immunity after the first dose of the vaccine kicks in within 12 to 14 days after it is given.
After a second dose of the Pfizer vaccine, the jab is 95 percent effective at protecting patients.
Israel is waiting 21 days between each dose as recommended by Pfizer and regulators.
UK health officials announced it would delay second doses of the Pfizer and Oxford vaccines in order to inoculate more people across the nation.
But scientists in Israel have questioned the UK Government’s tactics.
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Israel secured access to large amounts of the Pfizer jab after agreeing to provide data about its citizens so the company can track how well the vaccine works.
Professor Ran Balicer, epidemiologist and chief innovation officer for Clalit, the largest healthcare provider in Israel, told Sky News: “We compared 200,000 people above the age of 60 that were vaccinated. We took a comparison group of 200,000 people, same age, not vaccinated, that were matched to this group on various variables.
“Then we looked to see what is the daily positivity rate… And we saw that there was no difference between vaccinated and unvaccinated until day 14 post-vaccination.
“But on day 14 post-vaccination, a drop of 33% in positivity was witnessed in the vaccinated group and not in the unvaccinated… this is really good news.”
However, in the UK scientists claimed that trial data suggested it would be 89 percent effective after one dose.
The UK Government used the data to justify delaying the second vaccine dose for up to 12 weeks.
The Joint Committee on Vaccination and Immunisation said in a document: “Using data for those cases observed between day 15 and 21, efficacy against symptomatic COVID-19 was estimated at 89%, suggesting that short term protection from dose 1 is very high from day 14 after vaccination.”
Professor Baclicer said: “The data and estimates I gave are what we have.
“We could not see 89 percent reduction in the data we reported. Further data and analyses will be released in peer reviewer scientific format.”
He added: “The practice in Israel is to provide the second vaccine at three weeks. And so it is impossible for us to tell what would be the impact of not providing the second dose…”
Sir Patrick Vallance, the UK’s chief scientific advisor, has defended the strategy.
On Wednesday he said he would expect all vaccines to be less effective in the real world than in trials.