Another good article on CV antibody tests and CV immunity. [View all]

People who think they’ve been exposed to the novel coronavirus are clamoring for antibody tests — blood screens that can detect who has previously been infected and, the hope is, signal who is protected from another case of Covid-19.

But as the tests roll out, some experts are trying to inject a bit of restraint into the excitement that the results of these tests could, for example, clear people to get back to work. Some antibody tests have not been validated, they warn. Even those that have been can still provide false results. And an accurate positive test may be hard to interpret: the virus is so new that researchers cannot say for sure what sort of results will signal immunity or how long that armor will last.

They caution that policymakers may be making sweeping economic and social decisions — plans to reopen businesses or schools, for example — based on limited data, assumptions, and what’s known about other viruses. President Trump last week unveiled a three-phased approach to reopen the country; he said some states that have seen declining case counts could start easing social distancing requirements immediately. And some authorities have raised the idea of granting “immunity passports” to people who recover from the virus to allow them to return to daily life without restrictions.

“Before we embark on huge policy decisions, like issuing immunity certificates to get people back to work, I think it’s good that people are saying, ‘Hold up, we don’t know that much about immunity to this virus,’” said Angela Rasmussen, a Columbia University virologist.