This week, several over-the-counter Covid-19 tests were authorized by the Food and Drug Administration for use without a prescription, offering a way for schools, workplaces and other groups to conduct rapid screening.
The antigen tests offer faster results with less lab work and can be used to quickly and frequently test people to catch, in particular, those who are asymptomatic and at risk of unknowingly spreading the virus.
According to the FDA, rapid antigen tests will be especially useful for serial testing, which involves testing the same individual multiple times within a few days, and can increase chances of detecting asymptomatic infection that might not always show up with a single test.
“Screening testing, especially with the over-the-counter tests, is an important part of the country’s pandemic response—many schools, workplaces, communities, and other entities are setting up testing programs to quickly screen for COVID-19. With the FDA’s authorization of multiple tests, the public can be assured these tests have met our scientific standards for emergency use authorization. As we’ve said all along, if it’s a good test, we’ll authorize it,” said Jeff Shuren, M.D., J.D., director of the FDA’s Center for Devices and Radiological Health.
Antigen tests are designed to detect fragments of viral proteins that trigger an immune response in the body. These tests are not as sensitive as polymerase chain reaction, or PCR, testing, which has been the main method of screening for Covid-19. As such, it's possible for antigen tests to deliver false negative results, which makes frequent testing even more important.
"Frequent rapid testing will be important in the months and years to come as we understand more about how long immunity lasts from the vaccine and how variants evolve," Dr. Michael Mina, an assistant professor of epidemiology at Harvard University's T.H. Chan School of Public Health, said in a statement.
"We know that frequent testing with rapid results is critical because anyone can be exposed to this virus and not realize it until after they have become infectious," Mina said. "The best way to combat spread is to give people the tools to know that they are infectious in real-time."
Sources: NBC News, FDA