Too Soon To Start Issuing "Seine Covid Papieren"

technologyreview |  Imagine, a few weeks or months from now, having a covid-19 test kit sent to your home. It’s small and portable, but pretty easy to figure out. You prick your finger as in a blood sugar test for diabetics, wait maybe 15 minutes, and bam—you now know whether or not you’re immune to coronavirus. 

If you are, you can request government-issued documentation that says so. This is your “immunity passport.” You are now free to leave your home, go back to work, and take part in all facets of normal life—many of which are in the process of being booted back up by “immunes” like yourself. 

Pretty enticing, right? Some countries are taking the idea seriously. German researchers want to send out hundreds of thousands of tests to citizens over the next few weeks to see who is immune to covid-19 and who is not, and certify people as being healthy enough to return to society. The UK, which has stockpiled over 17.5 million home antibody testing kits, has raised the prospect of doing something similar, although this has come under major scrutiny from scientists who have raised concerns that the test may not be accurate enough to be useful. As the pressure builds from a public that has been cooped up for weeks, more countries are looking for a way out of strict social distancing measures that doesn’t require waiting 12 to 18 months for a vaccine (if one even comes).

There are some serious problems with trying to use the tests to determine immunity status. For example, we still know very little about what human immunity to the disease looks like, how long it lasts, whether an immune response prevents reinfection, and whether you might still be contagious even after symptoms have dissipated and you’ve developed IgG antibodies. Immune responses vary greatly between patients, and we still don’t know why. Genetics could play a role.

“We’ve only known about this virus for four months,” says Donald Thea, a professor of global health at Boston University. “There’s a real paucity of data out there.” 

SARS-CoV-1, the virus that causes SARS and whose genome is about 76% similar to that of SARS-CoV-2, seems to elicit an immunity that lasts up to three years. Other coronaviruses that cause the common cold seem to elicit a far shorter immunity, although the data on that is limited—perhaps, says Thea, because there has been far less urgency to study them in such detail. It’s too early to tell right now where SARS-CoV-2 will fall in that time range