The writer is a senior fellow at Harvard University and advises the UK Department of Health and Social Care

It feels almost quaint now, but in early March I was at a party in Manhattan. People had just about stopped shaking hands, but Sixth Avenue was still teeming. As we were served drinks, gazing out over the bright lights from a glass and steel tower, I was approached by a work-hard-play-hard 20-something who works on Wall Street. “I’m off to Florida tomorrow to sit this thing out,” he confided. “It feels less jam-packed there.”

At the time, I didn’t fully appreciate the implications. But it’s now clear that Covid-19 poses a profound challenge to a significant modern trend: megacities. Big urban centres are the new plague pits. New York City, America’s most crowded big city, has suffered about 23 per cent of all US deaths from the virus; London’s share of UK deaths is also 23 per cent; Madrid about 32 per cent; and Stockholm even more, according to researcher Joakim Book.

Density has been the enemy in most plagues. London’s Embankment was built to provide the city with a modern sewage system after thousands died in the cholera Pandemic that hit the city in 1854. The connection to dirty water was made by John Snow, a doctor who spotted clusters of sickness around a Soho water pump. Then came Ebenezer Howard’s concept of the “garden city”, which offered hygiene and greenery at the end of a railway line.

Will the suburbs become more attractive after this crisis? The trade-offs have changed. We used to put up with Living in cramped shoeboxes to be part of the “scene”. But if social distancing kills the scene, if offices are empty and people work four days a week from home, there is less reason to put up with the pollution, crime and grind. Almost overnight, cities have gone from being places of dreams and ambition to fearful symbols of mortality. The rich have retreated to the countryside, just as they did in Europe during the Black Death.

Until now, cities have always bounced back. The need to strike deals, ship goods and exchange ideas has inexorably drawn talent and cash. Jobs have migrated to cities, and people with them. One of this crisis’s most striking images was a Bangkok bus station, as 80,000 recently unemployed people tried to return to their home provinces. Yet this may be about to change.

In service economies, it may be cheaper for companies to operate from suburban towns. With the digital capability to work from home, people may not need to relocate to move jobs. They may prefer a house to that shoebox, with a longer commute one or two days a week. Even before coronavirus struck, this death-of-distance had made metropolitan living less essential. The populations of Paris, New York, Beijing and Shanghai were declining before the pandemic, partly due to punishingly high rents.

An unexpected consequence might affect family size. Big, successful cities are arduous places to bring up children. Singapore, Tokyo, Hong Kong, Shanghai and Beijing, some of the world’s most expensive cities, also have some of the lowest birth rates. If couples could move out and get a garden without sacrificing their careers or bankrupting themselves, they might be more likely to contemplate starting a family. An exodus to the suburbs or countryside might also start to reverse the geographical gulf between rural grandparents and children, especially acute in Asia. Just as the crisis has exposed the desperate plight of so many older people living alone, so it might prompt a gradual return to more generations living closer together.

It is not inevitable that the grim reaper will scythe through cities. Singapore and Hong Kong have had success containing the virus, through the tracking and monitoring systems they built after the 2003 Sars outbreak. Singapore banned travellers from mainland China in January, and has extensive infection control legislation which allows it to jail people who break quarantine. In future, the safest cities may be those with the most surveillance. That doesn’t sit easily with the freewheeling attractions of western cities, yet. The attitudes of Generation Z could prove decisive.

The desire to remain anonymous has long been a feature of metropolitan living. People move to the city to escape small towns where everyone knows their business. But this pandemic has unleashed an urge for more connection. The spread of local groups to support the vulnerable has brought together neighbours who never gave each other the time of day before. People who moved to cities to escape the parochialism of their childhoods are now frantically building what I can only describe as villages. These will surely endure because you cannot “unsee” a person once you have helped them, or they you.

If the pandemic calls into question the value of city life, not all cities will prosper equally. In a 2016 report on “the declining cost of distance”, consultancy Bain predicted that cities with green, walkable centres — New York, Paris, London and San Francisco — would retain their attraction for the young and wealthy. It also suggested that middle-income families would swap traditional suburbs for what it called “new villages” — low-cost residential zones with greenery and cultural amenities more than 50 miles from city centres.

Writing this, I suddenly felt an acute longing to be back in the swing of things. On a Zoom call, I jokingly offered to pop out and get everyone a skinny latte. All this suggested a longing for office life which, for me, is currently anchored in London. But could it be somewhere else? Maybe. I got in touch with a friend of the gentleman who evacuated to Florida. “They’re still there,” she said. “They love it.” The era of the megacity may be over.