Are antibody tests useful in determining immunity to Covid-19? Elizabeth Tracey reports


Antibodies are proteins that circulate in the blood and act as first responders to viruses, hopefully warding off infection. Antibodies are produced either in response to immunization or natural infection, but whether they provide a useful measure of protection is unclear. That’s according to Stuart Ray, an infectious disease expert at Johns Hopkins.

Ray: There’s the formal question of whether the antibodies measure the thing that we’re trying to detect. The other is whether there’s a correlation that’s useful, and whether we can identify people at risk in a reliable way. Neutralizing antibody assays can measure something but we don’t know exactly where the threshold is for protection. We can try to make some inferences but even that estimate, with the best estimates we have, is imperfect. But both because we don’t exactly know what level and we’re only measuring one particular function, there’s lots of reasons why there’s uncertainty.  :29

Ray says attempts to use neutralizing antibody levels against Covid-19 are a case in point for this uncertainty. At Johns Hopkins, I’m Elizabeth Tracey.