Daily or near-daily testing could be the key to opening our society, and that comes down to making the tests widely available and affordable. If you had the option to test yourself in the morning by spitting into a tube (or swabbing your nose) and waiting 15 minutes for the results, and if it cost you no more than a couple of dollars, wouldn’t you jump at that chance?

Mina breaks down the existing tests into two camps. “Espresso coffee” tests are reverse transcriptase polymerase chain reaction (RT-PCR) tests or deluxe antigen tests, and several manufacturers, like Mesa Biotech, Quidel and Becton, Dickinson, have already been granted Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA). These tests are highly sensitive, require a machine to churn out the results, and are expensive—anywhere from $30 to $150 per test. They also may have longer turnaround times; even Yale University’s SalivaDirect, which just received EUA on August 15 and costs only about $10, must be submitted to and processed by a central laboratory.

In sharp contrast lie the “instant coffee” rapid paper antigen tests, including one made by E25Bio, and one under development by 3M and MIT. These are fast, simple to use, at-home tests, and some are really inexpensive: about $1 to $5 per test. They are called lateral flow assays, but manifestly they are paper-strip tests that have an antibody embedded on filter paper. If a saliva sample has coronavirus present, the antibody will bind that viral antigen, turning the test positive, much like a pregnancy test works. Though the tests have much lower sensitivity than PCR tests overall, one advantage they have is that they do not detect leftover, inactive viral RNA particles, which may be present days to weeks after a person is infectious.