British Prime Minister Boris Johnson plans to reopen England's economy from coronavirus lockdown on July 19, but if he does so, it won't be without disquiet from some of the scientists whose advice he has followed thus far.
Despite one of the world's highest vaccination rates, Britain is facing a new wave of Covid-19. Johnson is taking a gamble: rather than shutting the country down, he is aiming to live with the virus in what is a world-first test case of the ability of vaccines to protect from the Delta variant. (Graphic on global vaccinations)
Johnson has already delayed the so-called "freedom day" by four weeks to allow more people to get vaccinated, after warning that thousands more people might die because of the rapid spread of the more infectious variant.
But with more than 86% of adults now having received a first dose and nearly two-thirds of adults fully vaccinated, Johnson has set July 19 as a "terminus" date for restrictions.
Anne Cori, an Imperial College epidemiologist behind one of the models that informed Johnson's initial decision to delay "freedom day", said it was premature to declare that the country can live with rising cases. Another delay to removing restrictions would be beneficial, she told Reuters.
"I think delaying buys time, and we have interventions in the pipeline that may help reduce transmissibility," Cori said, referring to booster shots and the possible vaccination of children, a step Britain has yet to decide to take.
Over 100 scientists have written to the Lancet medical journal calling Johnson's plan to lift all restrictions "dangerous and premature", adding a strategy to tolerate high levels of infection was "unethical and illogical."
But Johnson's government says it has more than just the epidemiological perspective to consider, and is reconciled to more deaths from Covid.
New health minister Sajid Javid has cited other health, education and economic issues that have built up during the pandemic as driving the need to return to normal, even if cases could reach 100,000 a day.
An intense debate has erupted between those who believe that the summer school holiday holds the best hope for lifting restrictions this year, and those who believe that Johnson - accused of having brought on one of the world's highest fatality rates by waiting too long to order previous lockdowns - is making another mistake.
In the case of the highly contagious Delta variant, vaccines appear to do a better job of preventing deaths and severe disease than of halting transmission. As a result, while Britain has been experiencing a sharp rise in cases this summer, deaths have not risen as quickly.
Infections on a seven-day average have now exceeded 25,000 a day, more than 10 times the level in mid-May. So far, however, the average number of fatalities per day has held below 30 since mid-April, proof, say scientists, that vaccines are saving lives.
Still, there are warning signs: Britain is currently seeing about 350 hospitalisations a day from Covid-19. While that's a fraction of the rate at comparable points in previous waves, it is up around 45% over the last 7 days.
In Israel, also among the world's fastest countries to deploy vaccines and first to ease lockdown, infections have risen recently, prompting the government to consider reimposing some restrictions even though serious illness and deaths still remain low.
Tim Spector, a King's College London epidemiologist who runs the research project ZOE Covid Symptom Study app, said he welcomed the government's recognition that the population must learn to live with the coronavirus.
But he questioned steps such as announcing an end to the mandate to wear face masks, which costs nothing to the economy and could help protect vulnerable people as well as young people from the impact of long Covid.
"There are things we can all do, that don't affect the economy ... and I don't think that's been quite emphasised enough," he told Reuters.
The British government is due to present updated models on July 12 from Imperial, Warwick and the London School of Hygiene and Tropical Medicine, the date that Johnson is expected to make his final decision on whether to lift restrictions a week later.
England's Chief Medical Officer Chris Whitty said modelling now suggested the peak would not lead to the same pressures seen during January.
David Spiegelhalter, chair of the Winton Centre for Risk and Evidence Communication at Cambridge University, said that the situation was delicate.
"This is an experiment, and I think we've got to call it that," he told Reuters. "I respect the judgments by Chris Whitty and others who say that if you're going to do this, this is the right time to do it."