As part of President Biden's recent "Path out of the Pandemic" plan, increased testing was flagged as an important part of containing the spread of COVID-19. The plan indicates nearly US$2 billion will be spent procuring 280 million rapid COVID-19 tests. Plus, major retailers will be required to sell these tests at cost, approximately 35 percent less than current prices.

These numbers certainly sound big – 280 million tests is a lot. But what is the best way to use these rapid tests? How accurate are they? And is the government underestimating how many tests will actually be needed to make a difference?

What is a rapid antigen test?

The gold-standard test for SARS-CoV-2 is known as a reverse transcriptase-polymerase chain reaction (PCR) test. This test, involving the infamously fun experience of having a swab inserted deep into one's nasal cavity, looks for viral RNA.

PCR tests are incredibly accurate. So much so they can pick up minute traces of viral RNA that may only result in innocuous asymptomatic infections, or even offer positive diagnoses weeks after a person has passed their infectious phase.

But PCR testing is also time and energy intensive, requiring samples to be sent to diagnostic laboratories. At best, the results of a PCR test can take several hours. And at worst, when labs are overwhelmed, it can be days before a result comes back.

Rapid COVID-19 tests, on the other hand, sacrifice a degree of accuracy for speed and simplicity. These tests look for proteins on the surface of viruses called antigens, or antibody generators.