Covid-19 antigen tests may not detect all cases of the novel coronavirus, but they could prove useful because they are inexpensive and people can use them at home, unlike other much less accessible tests, reports Scientific American

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. Deborah Birx, the White House’s coronavirus-response coordinator, has 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. On September 28, several months after this story was originally published, the Trump administration announced a plan to distribute 150 million of these assays, developed by Abbott Laboratories. The test, called BinaxNOW, correctly identifies 97.1 percent of positive cases and 98.5 percent of negative cases, and it provides results in 15 minutes.

Read more in Scientific American