The past three months have been a global experiment to test whether modern economies built on social interaction are compatible with methods for tackling a pandemic that haven’t moved on much since the Black Death.

The results are now in. Lockdowns are toxic for a world in which people travel to work on buses or commuter trains, spend eight hours with their colleagues at the office, spend their lunch hour doing a bit of shopping, and head off in the evening to the pub, the theatre or the football.

Britain imposed severe restrictions towards the end of March. By the end of April, according to initial estimates by the Office for National Statistics, the economy had shrunk by 25%. If anything, that will prove to be optimistic because of the difficulty in getting data from companies forced to close.

Little by little, restrictions are being lifted but life is not going to return to normal while face masks are obligatory on public transport, diners have to stay two metres, or even a metre apart in restaurants and customers are discouraged to browse in shops.

Recovery will be even slower in the event of a second wave of infections, something the history of past pandemics suggests is probable. Covid-19 looks to be the sort of virus that sticks around. The number of new cases has been on a downward trend for weeks as a result of the severest curbs on the UK population ever imposed in peacetime and the arrival of warmer weather, but what happens in the autumn when restrictions have been further eased and the temperature starts to drop? If the trend is reversed, does the government lock down the economy a second time?

The answer is almost certainly not, even though the possibility spooked financial markets last week. Share prices crashed in the early stages of the crisis because investors grasped that measures taken to control the pandemic would result in much weaker corporate profits. Markets subsequently rallied fast because the tentative easing of lockdown restrictions raised hopes of a V-shaped recession. They then had second thoughts after an increase in new Covid-19 cases in a number of US states, mainly in the south. The city of Houston in Texas is mulling the possibility of again ordering people to stay in their homes. A partial shutdown has been imposed in Beijing after the city reported its first cases of Covid-19 in almost two months.

This is likely to be the template for the months ahead: a targeted, localised approach rather than a blanket ban on activity. Political leaders are going to be wary of reimposing full lockdowns, and they are right to be.

For a start, it has become clear that there is no such thing as “the science” when it comes to Covid-19. Immunologists have different views about infection rates and possible mortality outcomes in the same way that monetarists and Keynesians differ over economics.

Ministers felt they had no option but to adopt a safety-first approach when the crisis broke in March because there was a genuine risk that an uncontrolled pandemic would overwhelm the NHS. Every person who had contracted the virus was infecting three others.

Three months later things look different. The NHS coped and the extra capacity installed through the Nightingale hospitals was not needed. The R number – the reproduction rate at which the virus spreads – has come down from three to one or just below.

Evidence of the harmful side-effects of the lockdown have also emerged. The number of suicides is up. Domestic violence has increased. Mental health is suffering. Unemployment figures out this week will illustrate the human cost of a 20.4% drop in national output in just one month. The jobless total is heading for 3 million this summer despite the fact that the government is currently paying a third of the workforce.

As the Institute for Fiscal Studies pointed out last week, the crisis has deepened Britain’s class, ethnic, gender and generational divides. Young people are the least likely demographic group to be infected with Covid-19 but they are being particularly hard hit by the lockdown. The cost of school closures for all children, but especially those from poorer households, will be high. The 18-24 age group are most likely to end up unemployed because many of them work in hospitality, retailing and leisure.

The likelihood that Covid-19 will resurface a second and perhaps a third or fourth time makes the case for a measured approach to future lockdowns even stronger. All the evidence is that six months without going to school is more than twice as damaging as three months. The same applies to youth unemployment. The longer the spell out of work the deeper the scars.

Getting young people to abide by a second lockdown would be problematic. They want to work, to meet their mates, go on demonstrations and have some fun. They know they are low risk and will do their own cost-benefit analysis. Many will simply not comply, deciding instead that Covid-19 is a risk they are prepared to accept.

This is not a bad philosophy because until a vaccine is found there is a choice. Either countries such as Britain use effective track and trace systems to deal with local hotspots and let the rest of the country operate as near to normal as possible, or they shut everything down again. If they haven’t already done so, governments will conclude that the economic, social, health and educational costs of full lockdowns are too high and that somehow we have to learn to live with Covid-19.