“In the absence of a vaccine, cure, or massive testing and quarantine, lockdowns and stay-at-home orders will need to last for months,” they wrote.

The researchers – Gerard Tellis from Marshall School of Business of the University of Southern California, Ashish Sood of the University of California Riverside’s A. Gary Anderson Graduate School of Management, and Nitish Sood, a cellular and molecular biology student at Augusta University – based their findings on an examination of 36 countries and 50 US states.

Tellis said that differences could also depend on “size of country, borders, cultural greetings (bowing versus handshaking and kissing), temperature, humidity, and latitude”.

Coronavirus latest: over 1 million people infected worldwide

“Singapore and South Korea adopted the path of massive test and quarantine, which seems to be the only successful alternative to costly lockdowns and stay-at-home orders,” Sood wrote.

They said the US faced a unique challenge because only half of the country’s states had adopted aggressive intervention, and done so at varying times.

At the start of last month, when the US reported around 1,000 coronavirus cases and dozens of deaths, US officials said that the infection risk for the American public was low.

Case numbers have risen exponentially over the past two weeks, with the country reporting 213,372 cases by Thursday.

Britain reversed its initial “herd immunity” strategy to cope with the coronavirus and introduced social distancing measures, banning large gatherings and closing schools, pubs, restaurants, gyms, and cinemas.