The US Food and Drug Administration confirmed on Monday it had given emergency use authorization to a new Roche antibody test that the company says is more accurate.
The drug giant announced the test had been authorized on Sunday, but the FDA did not update its website with a list of authorized tests until Monday.
Antibody tests look for evidence that someone has been infected with a virus, usually in the past. They can be used to see how many people in the population have been infected, even if they did not show symptoms. They may begin to show if people develop any kind of immunity to coronavirus, either in the short term or the long term.
They are different from the tests usually used to detect current infections. Those tests look for evidence of the virus itself in a patient.
Public health experts have complained that most of the antibody tests now on the market are inaccurate. Even a test that claims to have 95% accuracy can miss up to half of cases if the virus is not very common in the population being tested.
Roche said its test catches 99.8% of people who have been infected and identifies 100% of those who have not – a sensitivity of 99.8% and a specificity of 100%.
Better specificity averts the risk of false positives – a test that wrongly tells someone they have been infected when they have not been. If people do develop immunity to coronavirus infections, false positives would be dangerous because they could give people a false sense of security.