What is the next step after tests that can detect the presence of Covid-19 antibodies in individuals’ blood? Tests that can tell how many there are. That is the theory behind the FDA issuing emergency use authorisations to two new assays from Siemens Healthineers – the Advia Centaur COV2G and Atellica COV2G. These are semi-quantitative tests, meaning that they do not display a precise measurement, but estimate the quantity of antibodies against the coronavirus in a person’s blood. Over time, correlating antibody titres using tests like these with the patients’ record of reinfections could, in theory at least, help indicate what levels might constitute immunity. For now, the agency explicitly pointed out that there is still no proven link between the presence of antibodies and protection against reinfection with the virus, and warned that a positive result from these or any other antibody test does not mean it is safe to stop social distancing or wearing masks, or assuming it is safe to return to work.
Note: "Other" includes two antigen tests, two home sampling kits and one IL-6 test.