https://www.scientificamerican.com/article/breakthrough-covid-19-tests-are-currently-cheap-fast-and-not-very-accurate/

An inexpensive coronavirus test that millions of Americans could use at a pharmacy, in a workplace or even at home could prove to be a vital asset in allowing people to return to jobs and school. Last week Deborah Birx, the White House’s coronavirus-response coordinator, called rapid antigen tests the “breakthrough innovation” that is needed to perform hundreds of millions of such assays a day. The remarks echoed her previous statements that antigen tests might be used to examine broad swaths of the public.

The technique often involves a technology—called a lateral flow assay—similar to that employed in home pregnancy tests. In the test, an antibody can bind to one of the spike proteins (the antigens) that cover the surface of the virus like the spines on a puffer fish. The tests are inexpensive to produce and simple to use, and they deliver results in minutes.