Inexpensive testing strategies that provide near real-time results are critical for stopping the spread of coronavirus in communities and getting people back to workplaces and schools. Current testing strategies (namely the diagnostic, polymerase chain reaction (PCR) tests) do not accomplish this goal. Though useful for confirming the presence of SARS-CoV-2, PCR testing has been characterized by prohibitive costs and slow turnaround times, which hampers a timely public health response and thus, limits our ability to slow the rate of infection in our communities.
Rapid diagnostic testing (RDT) platforms exist, both molecular and antigen based; however, due to manufacturing constraints these devices are not yet readily available on a large scale to patients outside of Indian health services, remote clinics and nursing home facilities where these devices have been prioritized. If more readily available, these devices could be widely deployed to pharmacies with a CLIA waiver to make testing more widely available with more immediate results. 93% of Americans live within 5 miles of a pharmacy so this would provide the ideal access points for mass testing needs. These same devices could also perform rapid flu and strep testing, which would help to better pinpoint the type of outbreak occurring as we approach the cold and flu season with overlapping coronavirus.
Frequent, widespread usage of inexpensive antigen tests (which measure viral proteins rather than the genetic material) could help solve this problem. Distinct from rapid diagnostic testing, these point-of-care, self-administered antigen tests are to be used as a public health screening measure rather than a clinical diagnostic tool. Because of lower sensitivity (their inability to detect very low viral load—i.e. the concentration of viral particles in a sample), their principal utility lies in their ability to identify individuals most likely to be infectious to others so they can be isolated and drive down community spread of the virus. Discussed at length by experts in the publications below, these novel testing strategies could be the key to slowing the spread of SARS-CoV-2.
To date, several academic and private laboratories are developing variations of these tests. Developers include: E25Bio from Harvard University, and labs at the University of Illinois (though it remains unclear whether this test will be used for their student body alone). A test that has gained attention in recent days is the Yale University SalivaDirect saliva-based test, which gained FDA emergency use authorization on August 15, 2020. Although it is a step in the right direction, with testing made simpler (saliva versus nasopharyngeal swab), cheaper, and faster (half the processing time of traditional PCR), we need to push for true, point-of-care, at-home testing to truly meet the widespread needs mentioned above.
The SAFE team is monitoring developments in the field, including new authorizations from the FDA as well as communicating with developers and distributors, so that when these tests are available, we will be able to incorporate these technologies into our screening strategies.
Bibliography and additional reading
Freese KE. Want to reopen schools safely in Arizona? Then roll out rapid, daily testing. Arizona Republic. August 11, 2020
Kotlikoff LJ and Mina M. A cheap, simple way to control the coronavirus. The New York Times. July 3, 2020
Jha AK. American needs to radically rethink out COVID-19 testing approach. TIME. July 29, 2020
Vogels CBF, et al. SalivaDirect: simple and sensitive molecular diagnostic test for SARS-CoV-2 surveillance. medRxiv (preprint). August 4, 2020