Dominic Raab has said the government has no plans to publish the list of participants in the Sage committee of scientific experts, after the Guardian revealed that key meetings have been attended by Dominic Cummings.

“We don’t release as a matter of practice the names of all the members of Sage because the risk of them being subject to pressure, undue influence,” the first minister and foreign secretary said on Sunday.

He rejected the idea there had been a “lack of transparency” from the government over the group’s work.

“We’ve had the chief scientific adviser, Sir Patrick Vallance, the chief medical officer, Prof Chris Whitty, along with politicians like me standing up on a daily basis answering the questions, setting out their advice and making sure that we communicate as clearly as possible to the public what that advice is,” he said.

Some senior Conservatives, including the former cabinet minister David Davis, have joined calls for more information to be published about the committee’s deliberations.

Ministers have repeatedly insisted throughout the crisis that they have “followed the science” – so the presence of Cummings and another political adviser, Ben Warner, at some committee meetings has raised questions about its independence.

Davis said: “We should publish the membership of Sage, remove any non-scientist members, publish their advice in full, and publish dissenting opinions with the advice.”

Speaking to Sophy Ridge on Sky News, Raab underlined the risks of a “second spike” in the coronavirus outbreak, and declined to set out details of when and how the lockdown could be lifted across the UK.

The foreign secretary said ministers were beginning to examine what should happen in what he repeatedly called the “second phase” of the lockdown: but he also stressed the importance of avoiding a resurgence in infections by lifting restrictions too soon.

“There are certain things that if we jumped the gun, they would be irresponsible and precarious,” Raab said. “The delicate stage we’re at, is if we ease up too soon, we risk a second spike of the virus,” he said, speaking to Sophy Ridge on Sky News.

Quick guide Will there be a second wave of coronavirus? Show Hide In recent days the UK has seen a sudden sharp increase in Covid-19 infection numbers, leading to fears that a second wave of cases is beginning. Epidemics of infectious diseases behave in different ways but the 1918 influenza pandemic that killed more than 50 million people is regarded as a key example of a pandemic that occurred in multiple waves, with the latter more severe than the first. It has been replicated – albeit more mildly – in subsequent flu pandemics. Until now that had been what was expected from Covid-19.

How and why multiple-wave outbreaks occur, and how subsequent waves of infection can be prevented, has become a staple of epidemiological modelling studies and pandemic preparation, which have looked at everything from social behaviour and health policy to vaccination and the buildup of community immunity, also known as herd immunity. Is there evidence of coronavirus coming back in a second wave? This is being watched very carefully. Without a vaccine, and with no widespread immunity to the new disease, one alarm is being sounded by the experience of Singapore, which has seen a sudden resurgence in infections despite being lauded for its early handling of the outbreak. Although Singapore instituted a strong contact tracing system for its general population, the disease re-emerged in cramped dormitory accommodation used by thousands of foreign workers with inadequate hygiene facilities and shared canteens. Singapore’s experience, although very specific, has demonstrated the ability of the disease to come back strongly in places where people are in close proximity and its ability to exploit any weakness in public health regimes set up to counter it. In June 2020, Beijing suffered from a new cluster of coronavirus cases which caused authorities to re-implement restrictions that China had previously been able to lift. In the UK, the city of Leicester was unable to come out of lockdown because of the development of a new spike of coronavirus cases. Clusters also emerged in Melbourne, requiring a re-imposition of lockdown conditions. What are experts worried about? Conventional wisdom among scientists suggests second waves of resistant infections occur after the capacity for treatment and isolation becomes exhausted. In this case the concern is that the social and political consensus supporting lockdowns is being overtaken by public frustration and the urgent need to reopen economies. However Linda Bauld, professor of public health at the University of Edinburgh, says “‘Second wave’ isn’t a term that we would use at the current time, as the virus hasn’t gone away, it’s in our population, it has spread to 188 countries so far, and what we are seeing now is essentially localised spikes or a localised return of a large number of cases.” The overall threat declines when susceptibility of the population to the disease falls below a certain threshold or when widespread vaccination becomes available. In general terms the ratio of susceptible and immune individuals in a population at the end of one wave determines the potential magnitude of a subsequent wave. The worry is that with a vaccine still many months away, and the real rate of infection only being guessed at, populations worldwide remain highly vulnerable to both resurgence and subsequent waves. Peter Beaumont, Emma Graham-Harrison and Martin Belam

He confirmed Boris Johnson would be back at work on Monday, three weeks after being taken into intensive care with Covid-19.

He said the prime minister would be “back at work full-time, properly, at the helm” – and “as you can imagine with the prime minister, he’s raring to go”.

Johnson will have to confront the challenge of deciding when, and how, to unravel the stringent lockdown measures imposed on 23 March, amid conflicting pressures. They are due to be reviewed by 7 May.

Johnson held a three-hour meeting at his country retreat of Chequers on Friday with Raab, the chancellor, Rishi Sunak, and key aides including Dominic Cummings.

Sunak is concerned about the devastating impact of the crisis on the economy, with the independent office for budget responsibility suggesting a three-month shutdown could lead to a 35% collapse in GDP and an increase of more than 2 million in unemployment.

At the meeting, Johnson reportedly quoted, in Latin, the Roman statesman Cicero, saying, “the health of the people should be the supreme law”.

Raab confirmed that travellers entering the UK could face further restrictions – including potentially health checks on entry – during the next phase of managing the crisis.

“That is something we will be looking at, and it could include the testing for people coming in; it could include social distancing measures,” he said.

He rejected the idea that ministers should have imposed such measures earlier.

Arrivals into Britain from the worst-affected countries were quarantined or urged to self-isolate during the early stages of the outbreak: but the measures were then lifted once it was clear the virus was spreading within the UK.

At the time, Raab said, ministers were advised that travel restrictions or quarantine measures would “make almost no impact on the spread of the virus because of the decrease in the number of people travelling, and the fact that the infection rate within the UK is high”.

The Scottish first minister, Nicola Sturgeon, echoed Raab’s caution about relaxing the rules, telling the BBC: “It’s too early right now to have any confidence that we could see the virus potentially run out of control again.”

She added that when measures could be lifted, “it’s not a flick of the switch moment: there will be a real need for care and caution and a slow and gradual process”.

She said social distancing would have to be in place for “quite some way to come,” and the public would have to contemplate “different ways of operating”.

Whitehall officials have been examining what kinds of businesses should potentially open first, based on which could safely impose physical distancing – and which are most critical for the economy and society.

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