USA – New blood test may detect SARS-CoV-2 antibodies

How many COVID-19 cases have gone undetected? And are those who had mild cases of the disease—perhaps so mild they dismissed it as a cold or allergies—immune to new infections? If so, they could slow the spread of the burgeoning pandemic.

Answering those questions is crucial to managing the pandemic and forecasting its course. But the answers won’t come from the RNA-based diagnostic tests now being given by the tens of thousands. They look for the presence of viral genes in a nose or throat swab, a sign of an active infection. But scientists also need to test a person’s blood for antibodies to the new virus, known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Such tests can detect active infections, too, but more importantly, they can tell whether a person has been infected in the past because the body retains antibodies against pathogens it has already overcome.

Labs and companies around the world have raced to develop antibody tests, and a few have been used in small studies and received commercial approval, including several from China. But so far, large-scale data from such tests—for example showing what fraction of people in the hard-hit city of Wuhan, China, might now be immune—is still lacking or at least not public. Scientists hope that will soon change as more tests become available…