Boris Johnson is to spend a second night in intensive care amid concerns about the seriousness of his condition and how the government will make key decisions about the coronavirus pandemic in his absence. The foreign secretary, Dominic Raab, who is deputising for the prime minister, has no power to make major decisions without cabinet agreement, it emerged on Tuesday. There are also doubts about whether lockdown conditions imposed by the prime minister will be reviewed as promised next week. Raab tried to strike a reassuring tone at the daily Downing Street press conference after Johnson was moved to intensive care on Monday evening because his condition had deteriorated 24 hours after he was admitted to hospital, saying: “He will pull through.” The prime minister required oxygen for breathing problems but No 10 said he had not been placed on a ventilator and did not have pneumonia. They did not reveal further details, such as whether Johnson had any type of secondary infection. Raab said: “I’m confident he will pull through because if there is one thing that I know about this prime minister, he is a fighter and he will be back leading us through this crisis in short order. The foreign secretary conceded that he and his cabinet colleagues were concerned about the situation, saying Johnson was “not just our boss – he is also a colleague and he is also our friend”. Giving an update on Johnson’s condition, Raab said: “He’s receiving standard oxygen treatment and breathing without any assistance, he’s not required any mechanical ventilation or non-invasive respiratory support. He remains in good spirits and in keeping with usual clinical practice his progress continues to be monitored closely in critical care.” A Downing Street spokesperson later confirmed Johnson, 55, would spend another night in the intensive care unit at St Thomas’ hospital in London. The news came as: The UK experienced its highest daily number of recorded coronavirus deaths, at 854 – a figure beginning to approach the toll on the deadliest days so far in Italy and Spain. Prof Chris Whitty, the chief medical officer for England, conceded that the UK should learn from Germany’s record on mass testing for coronavirus. The Queen sent a message of support to Johnson, his pregnant partner, Carrie Symonds, and his family, wishing him a rapid recovery, and well-wishes poured in from other royals, world leaders and politicians. It emerged that none of the four US drug company treatments that Donald Trump claimed could help Johnson recover from Covid-19 have been clinically tested for coronavirus or are available on the market. Downing Street indicated it did not wish to take up the offer of experimental drugs. While Raab, 46, is formally deputising for the prime minister, No 10 and Michael Gove, the Cabinet Office minister who is now self-isolating, stressed that any big decisions would have to be made collectively by the cabinet. Asked whether he would be able to change course if necessary – by easing or intensifying the lockdown, for example – Raab said: “I was given a very clear steer from the prime minister and as we have been going through this crisis, very clear instructions in terms of dealing with coronavirus – and he’s asked me to deputise for him as long as is necessary, but the normal cabinet responsibility and principles that inform that will apply.” He repeatedly declined to answer the question of whether the measures of closing pubs, restaurants, and non-essential shops, and limiting when the public can leave their homes, would be reviewed next Monday, three weeks after they were introduced. When the prime minister gave his televised address on 23 March, he told the public: “I can assure you that we will keep these restrictions under constant review. We will look again in three weeks, and relax them if the evidence shows we are able to.” Raab said only that the government would be guided by scientific evidence about the impact of the measures on the spread of the disease. Giving an update on the prime minister’s condition at the regular lobby briefing earlier, No 10 had said Johnson had received oxygen but had not been ventilated either in an invasive or a non-invasive way. His spokesman also said he did not have pneumonia, which can take months to recover from fully. Any change in his condition would be made public, the spokesman said. One intensive care consultant told the Guardian that the average expected stay for coronavirus patients in intensive care was three weeks, though this takes into account the need to be intubated and on a ventilator. The latest report on patients admitted into critical care for coronavirus in England, Wales and Northern Ireland since the outbreak began in February showed that only 15% of them had been discharged. A similar number had died and the rest remained in hospital. Whitty, who has only recently returned to work after contracting the virus, conceded that the UK should learn from Germany’s record on Covid-19 testing. “We all know that Germany got ahead in terms of its ability to do testing for the virus, and there’s a lot to learn from that,” he said. Germany is able to test 500,000 patients each week and is under pressure to increase this further. Whitty had interjected at the press briefing after the government’s chief scientific adviser, Sir Patrick Vallance, gave a more circumspect reply. Vallance said: “The German curve looks as though it’s lower at the moment, and that is important, and I don’t have a clear answer to exactly what is the reason for that.” The government’s response to the virus is being overseen by four cabinet committees, which are in turn overseen by a coordinating committee, which Raab chaired on Tuesday morning. Whitehall sources have denied reports of infighting between senior ministers, including the chancellor, Rishi Sunak, and the health secretary, Matt Hancock, over the handling of the outbreak, with one describing the notion that there are differences over how to exit from the lockdown as “absolute nonsense”. But ministers and their advisers face a series of fraught decisions in the coming days and weeks about how, and when, to lift restrictions. Johnson continued to chair the Covid-19 committee by video-link last week while self-isolating after testing positive for the virus on 26 March. Amid concerns that Johnson had been working too hard through his illness, Gove said the prime minister had “followed medical advice” at all times. In a round of broadcast interviews, Gove said the prime minister was fit, enjoyed tennis and had a “zest and appetite for life”, so the seriousness of his illness was “naturally concerning”.