The BioNTech/Pfizer Covid-19 vaccine is 85 per cent effective after the first dose, according to a new Israeli study that supports the UK’s decision to space out doses. 

A study of 9,000 healthcare workers found that a single dose reduced the number of people developing symptomatic Covid-19 by 85 per cent after a period of 15 to 28 days following inoculation.

The study, conducted by Sheba Medical Center, a leading research hospital, and published in The Lancet, found it also had an impact on asymptomatic infections, reducing all positive test cases by 75 per cent. 

The UK has been spreading out shots from both BioNTech/Pfizer and Oxford/AstraZeneca, giving the second doses 12 weeks after the first, as it tries to protect the population as quickly as possible. 

But BioNTech and Pfizer have said there is no evidence that spreading out the doses works. Other countries including Israel and the US are trying to stick more closely to the three-week gap proven in the clinical trial.

“This groundbreaking research supports the British government’s decision to begin inoculating its citizens with a single dose of the vaccine,” said Arnon Afek, deputy director-general of Sheba Medical Center.

Israel is leading the world in vaccinations after signing an agreement with Pfizer that allowed it to secure more doses by offering to study when they achieve herd immunity in the small country. 

The Sheba Medical study follows a February analysis that showed case numbers and hospitalisations dropping in Israel among vaccinated age groups, even though many had only received one shot. 

It also builds on a lab study that found that 91 per cent of doctors and nurses had a strong antibody response three weeks after receiving their first shot. 

Gili Regev-Yochay, director of the Infection Prevention and Control Unit at Sheba Medical Center, said the vaccine was “amazingly effective”. 

“Everybody’s showing pretty much . . . the same thing, so you know it means that this is obviously really true,” she said. 

The advantage of studying healthcare workers is that they all follow the same testing procedures, she said, so the data is not distorted by who decides to get tested.

But the study was dominated by a younger population, who are likely to have stronger immune responses, and it does not have data on how long the protection lasts because it only followed workers for the weeks until they got their second vaccination. 

However, Regev-Yochay said she would assume the immune response would last for “a long time”. “If it’s working so well in four weeks, then definitely, you can delay the second dose for a little longer,” she said.

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