A blood test to find out whether people have been infected with coronavirus in the past has been approved by Public Health England, a ‘very positive development’. The test looks for antibodies to see if a person has already had the virus and might now have some immunity. Until now, officials have said such tests are not reliable enough. The government previously spent £16m buying antibody tests which proved to be ineffective. This test is the first one to offer serious potential. Experts at Porton Down evaluated the test and found that if someone had been infected, it gave the correct result 100% of the time. And if someone had not caught coronavirus, then it gave the correct result in 99.8% of cases.