It doesn't say a single dose is 33% less effective than a double dose.
It is comparing likelihood of infection after 14 days, with a single dose or no vaccine at all.
One Israeli study says 33% less likely to contract another says 60% less likely. Pfizer say 52% less likely after 12 days.
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All eyes are on Israel. The speed of its vaccination programme will provide insights into how well the jabs work in the real world. Will they eradicate severe disease? Can they curb transmission?
The most eye-catching statement has come from Nachman Ash, Israel's coronavirus tsar, who said that a single dose of the Pfizer-Biontech vaccine appeared to be "less effective than we had thought".
This sounds ominous for Britain's strategy of
delaying booster injections to stretch supplies and give as many people as possible a first shot but it is not clear that Israel's experience warrants a change of policy.
https://www.mytimesplus.co.uk/events/covid-what-we-have-learnt-with-tom-whipple-and-andrew-gregory
A trial in the US by Pfizer suggested that a single dose was about 52 per cent effective in preventing people from developing Covid-19, defined as a positive test plus symptoms after 12 days.
One of the pieces of
disconcerting Israeli data has come from the Clalit Research Institute, a healthcare provider. It created two groups of similar patients over the age of 60, each of about 200,000 people. One had been vaccinated, the other had not.
Coronavirus cases in the two groups were about the same 12 days after injection. On day 14 the graphs diverged, with "a 33 per cent decline [in infections] among the vaccinated elderly, without a similar trend among the unvaccinated," Ran Balicer, the director of the institute, said.
The 33 per cent figure caused alarm: at first glance it looks as if the Pfizer trial had suggested a higher level of protection. But how many of the Clalit trial's vaccinated cohort who tested positive had symptoms? Were these mild and asymptomatic cases
Adding to the confusion, Maccabi, another Israeli healthcare provider, said that the first dose of the vaccine reduced the risk of catching coronavirus by 60 per cent after 14 days — above the Pfizer trial threshold. The joint committee on vaccination and immunisation, which advises on UK policy, has estimated short-term protection from one dose at about 90 per cent.
If you have a policy that involves giving one dose and delaying a booster, it would be good to be confident that it gave a good level of protection before a second shot.
The Israeli reports are a concern but they "are insufficient to provide any evidence that UK policy in regard to delaying the second dose is in any way incorrect", Stephen Evans, of the London School of Hygiene and Tropical Medicine, said.
Positive cases picked up by PCR tests are less important for the UK than hospital admissions and death, he said. "The UK will soon have its own data showing efficacy . . . any policy changes should await [that]," Professor Evans said.
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