If we know someone has had the virus, they can potentially leave their home without risk of being re-infected, which would help countries get moving again. However, the accuracy of the tests has yet to be established. “The one thing that’s worse than no test is an inaccurate test,” Chris Whitty, the UK’s chief medical adviser, said on 25 March. Someone wrongly told they have already had covid-19 could go out and get infected.

How accurate do the tests need to be? “It’s very difficult to say,” says Emily Adams at the Liverpool School of Tropical Medicine in the UK, who is helping assess the tests developed by Mologic, one of the companies supplying the UK. Part of that process will be working out what accuracy is required for different uses, says Adams.

Ideally, we want to find out whether the thousands of health workers who are currently self-isolating because they or someone else in their home have symptoms that might be covid-19 can get back to work. Unfortunately, the antibody test may not help with this.