Drug giant Roche says it has received FDA emergency use authorization for a new coronavirus antibody test, which it claims is more accurate than most of those on the market.
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 also begin to show if people develop any kind of immunity to coronavirus, either in the short term or the long term.
Antibody tests are different from the tests used to detect current infections, which look for evidence of the virus itself in a patient.
The US Food and Drug Administration has not yet confirmed that it has given Emergency Use Authorization to the Roche test.
Experts urge caution: 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.
Roche tested the assay in people who had been diagnosed with Covid-19 14 days previously using a diagnostic test called a PCR test.
Based on the measurement of a total of 5272 samples, the Elecsys Anti-SARS-CoV-2 assay has 99.81% specificity and shows no cross-reactivity to the four human coronaviruses causing common cold,” Roche said in a statement.
“This means it can lower the chance of false positives due to the detection of similar antibodies that may be present in an individual, but are specific for coronaviruses other than SARS-CoV-2.”
Roche says it has already started shipping the new antibody tests to leading laboratories globally, and will ramp up production capacity to high double-digit millions per month to serve healthcare systems in the US and other countries that accept US approval.
Read more on antibody tests here.