Data shows that the UK’s coronavirus outbreak is following a similar trajectory to Italy’s, with around a two-week delay. While panic will not help anyone, the only rational reaction to this information is serious alarm. On Saturday, 793 fatalities took Italy’s death toll, already higher than China’s, to 4,825. The pattern of exponential growth is repeated in other western countries including Spain.

If the disease advances in the UK as scientists expect, the number of people killed will increase from 281 to around 5,000 in about two weeks’ time. These are the brute facts that led to last week’s switch in government policy, with an approach focused on “mitigation” partially replaced with a more aggressive policy of “suppression”.

Having closed schools, bars and restaurants, the government on Sunday declined to go further – for example, forcing non-essential businesses to close. Instead, the prime minister announced a new programme to “shield” the 1.5 million people at highest risk – who will be asked to stay at home for 12 weeks. The danger is that the policy, which stops short of measures taken by other European governments, does not go far enough, particularly in London where cases are most concentrated.

Those who are able to should take steps beyond what the government has advised. That means working from home, unless this is impossible, or because your job is essential to the coronavirus effort (or the allied effort to support those who are unable to cope on their own). It means shopping rarely, keeping a safe distance of at least six feet from others, and following strict hygiene rules.

It also means being aware that the restrictions do not affect everyone equally. Families in overcrowded housing, for example, face far greater hardship as a result of school and other closures. Single people and those in unhappy or abusive family situations will suffer disproportionately from quarantining. Individuals as well as voluntary organisations and councils can help (for example, by leaving parks to those without gardens, and by checking on friends by telephone and online).

After wasting vital weeks that should have been devoted to preparations, the government has been playing catch-up. The lack of support for the UK’s 5 million self-employed workers in the package of measures announced by the chancellor last week is extremely concerning in light of survey findings that around half of those who are self-employed, or in irregular work, would continue working despite having the virus. Finding a mechanism to enable these people to stop work is a task that should already have been done, along with the ordering of ventilators, testing equipment and protective clothing for medical staff and others on the frontline.

Images of crowded streets and parks over the weekend were disturbing proof that the public has not grasped the fundamental importance of social distancing. Even more disturbing is the extent to which Boris Johnson is to blame. Last week’s suggestion that we could “send coronavirus packing in this country”, and the timescale of 12 weeks, was grossly irresponsible when scientists are clear that policies to limit transmission will be needed for at least a year. On Sunday, he again struck the wrong tone. Lacking the gravity and clarity of his own cabinet colleagues, as well as foreign leaders, he instead conveyed palpable resistance to the stronger measures that may be required to protect people’s lives.

Given expert predictions that the total number of UK deaths could be 250,000, the priority is to save lives. Saturday’s announcement of a partnership between the NHS and the private sector was a rare note of encouragement. A thorough investigation of the government’s decision to aim for mitigation and herd immunity, when the international consensus pointed to suppression, will have to wait.

But questions about Mr Johnson’s judgment and leadership cannot be brushed off. Weekend reports of a policymaking process in which the views of his adviser, Dominic Cummings, appear to have been given greater weight than scientists’, are deeply worrying. In a democracy of 70 million people, this is not how policy should be made. As we career into highly dangerous and uncharted waters, it is right to ask whether our ship’s captain is up to the job.