The U.S. Food and Drug Administration was given emergency approval for a first so-called serology test, which will detect antibodies to the coronavirus, showing who is immune to the fast-spreading virus.

The new tests, which could be released in the next few weeks, could show how widespread the virus is, who can safely return to work and possible treatments for those fighting the virus. The test will use a blood sample from a finger prick to determine if it contains antibodies to fight the virus, and it may be able to be used in the confines of a person’s home.

Dr. Elizabeth McNally, director of the Northwestern University Feinberg School of Medicine Center for Genetic Medicine, explained:

“They will come in a variety of shapes and sizes. The simplest would be one that you do at home, that you would poke your finger and squeeze out a little blood and put it on a little strip, and it’ll be the plus-minus whether you’ve developed antibodies or not. The people who are already covered can actually provide protection to the people around them, just because it’s hard for the virus to spread. The virus can’t spread anymore, so people are less likely to get it. Once the antibodies come up in your system, that means your body fought it off, and you don’t have active virus.”