One thing we should have learnt from the pandemic is that we are all in this together. Only shared endeavour can rein in the Covid-19 virus. Your face covering is my protection.

Boris Johnson, though, is fed up with the rules. Collective action, the UK prime minister says, must be replaced by “personal responsibility”. What he really means is that he intends to allow the virus to run free in a dash for what epidemiologists call herd immunity. The nation’s children will be unwitting pawns in the experiment.

The rate of new infections in the UK is above 25,000 a day — much higher than in most European states. No matter. After 18 months of vacillation, swerves and U-turns, Johnson says his new master plan is “irreversible”. On 19 July virtually all legal curbs on social interaction will be scrapped.

The new regime in England (Scotland, Wales and Northern Ireland set their own rules) will allow nightclubs to reopen, social distancing to end and uncapped crowds to return to sports grounds and music venues. Face masks will cease to be mandatory and individuals will have to weigh up the risks of attending “superspreader” events.

By the government’s own calculation, the result will be an explosion of infections. Johnson says the daily rate may climb to 50,000 cases by July 19. The health secretary Sajid Javid predicts this could double later in the summer. The impact will be felt overwhelmingly by the young — the unvaccinated under-18s and the 20-somethings who have had at most one dose. The under-18s alone account for about 20 per cent of the population.

Johnson does not like lockdowns. After failing to get a grip at the outset of the pandemic he has overpromised and underdelivered on restrictions. Former aide Dominic Cummings says the prime minister once declared he would rather allow bodies to pile up in the streets than tighten legal curbs. Johnson denies using those particular words, but Downing Street insiders say they offer a fair reflection of his mood. He had hoped to scrap the remaining legal restraints last month, but was forced to delay by the virulence of the Delta variant. Now he has told colleagues that, whatever the cost, he will not reverse himself again.

The result is a leap in the dark driven not by epidemiology nor by careful cost-benefit analysis of the present lockdown, but by prime ministerial temperament reinforced by the noisy demands of like-minded Tory MPs.

Johnson’s cover is the success of the vaccination campaign. By July 19, he says, two-thirds of the adult population will have received two doses of vaccine. And there is abundant evidence that the inoculation drive has sharply reduced the link between the incidence of the virus and the numbers being hospitalised or dying. Most people who now contract Covid-19 need no more than a few days rest. Many are asymptomatic.

The prime minister is telling half the story. A two-thirds vaccination tally leaves one-third with only partial or no vaccine protection. And the “double-jabbed” do not have complete immunity from infection. Even when those with natural immunity are discounted, this leaves a very large pool of susceptible adults. Add children and Covid-19 is spoilt for targets.

The clinically vulnerable and elderly are at immediate risk. They represent a small proportion of overall new infections but with cases rising at their present rate, a small proportion will produce high numbers. As for the children at the centre of Johnson’s experiment, they may shrug off the initial infection only to develop so-called long Covid.

Chris Whitty, the government’s chief medical adviser, warned this week that the only way to curb rising long Covid rates among children is to hold down infection rates and step up vaccination. But the government has yet to authorise vaccination of under-18s and the herd immunity strategy anyway rests on allowing the virus to rip among children.

If not now, when? The prime minister’s rhetorical question is easily answered. Restrictions should be lifted gradually when infections have been brought under control and vaccination is further advanced. Of course, we will have to live eventually with the presence of coronavirus, but the route to taming it is through vaccination rather than turning children into epidemiological guinea pigs.

Johnson may feel better for his bonfire of regulations. And some people doubtless are cheering the designation of July 19 as “Freedom Day”. It’s an illusion. Covid-19 is not about to be beaten by prime ministerial bluff and bluster about “personal responsibility”.