Apr 29, 2020
A quick look into the global state of testing for COVID-19, with links to resources for going deeper into understanding the advantages and disadvantages of testing solutions available now as well as a sampling of some of the promising solutions in-development
What would an ideal COVID-19 (SARS-CoV-2) testing solution look like? It could be performed at home, painlessly, inexpensively, and with fast and accurate results—something as easy and accessible as an over-the-counter pregnancy test.
In order to set an agenda for developing tests that begin to approach that ideal solution, we need first to understand the pros and cons of the main types of COVID-19 tests that exist now and what variations exist within each of those types of tests. Only then can we identify what paths researchers might take either to improve upon the current options or to develop new ones.
Today’s Testing - Molecular Testing
Perhaps the most well-known and widely used type of COVID-19 test in use today is molecular testing. Molecular testing deals with the DNA of the virus and the techniques for this analysis. Such testing is done by obtaining a nose or throat sample, then analyzing that sample for the presence of the virus. On the upside, such tests are reasonably accurate and many already are available under an FDA Emergency Use Authorization for the US. Multiple tests also can run in parallel, which offers some efficiency. That efficiency is offset, however, by the time (measured in hours) to obtain results. Another drawback is that it can only detect active infections. Even more importantly, molecular test analysis requires specialized equipment (a thermocycler that amplifies DNA) and requires trained staff working in authorized laboratories. (1) (2) (3)
Today’s Testing - Serological Testing
The limitations of requiring trained staff and authorized labs also apply to the second-most common type of COVID-19 test in use today called serological testing: tests of blood or other body fluids, which use chemical analysis to detect the presence of the virus (antigen-testing) or the presence antibodies (IgM and/or IgG) produced as a response to the viral infection in the blood. The most accurate form of such tests are known as enzyme-linked immunosorbent assays, ELISA. ELISAs are in general simple and easy to perform and it can be done in a hospital laboratory. However, it is not yet well established as a testing method (though it does become more popular every day). (2)
Less training is required for point-of-care staff for a different form of these tests, known as rapid diagnostic testing. However, such tests, which also offer the benefit of providing fast results without requiring special equipment, do not provide results sufficiently accurate to be relied upon for diagnosis. In addition, such testing is best done several days after infection. In the US there currently are two rapid detection tests which have Emergency Use Authorization (although others are authorized for use in other countries). (3) (4) (5)
Today’s Testing - Summary
We have provided a very light introduction to what are today’s COVID-19 primary testing solutions and what are some of the disadvantages that need to be addressed. We don’t have data covering global testing capabilities, but can assume that there is a need for more available solutions to test the broader population in most countries. For example, the US only performs roughly 10,000 molecular tests per day. (9) A good follow-up article that goes more in-depth into the solutions and provides more definitions and background is found here. (2)
The remaining types of COVID-19 testing are in experimental use or under development today involve new methods for screening, testing, and monitoring. There are a few promising solutions that only require saliva which makes getting samples easier and non-invasive. (6) One of these saliva based solutions being developed in Denmark uses photonics (ie light) to detect infections, with the promised benefits of speed, low cost, and availability of equipment to run the tests. (7)
Lack of supplies and proper lab equipment for conducting tests is also being addressed in the possible solutions using CRISPR gene technology. One solution out of India is a low cost rapid paper-strip test for detection within an hour using CRISPR technology to identify the genomic sequences of the virus. (10)
Solutions don’t always need to tick all the boxes, which is why we should still explore an array of solutions that might take different approaches to what is available today. For example, screening much of the population just by using AI to evaluate the sound of your cough with your smartphone. (8) Although the current accuracy of this method is only 70%, the ability to screen anyone at this level at zero cost is advantageous.
So, despite the presence of multiple options both today and tomorrow, the challenges to offering ideal COVID-19 testing remain substantial. Research is of course always ongoing into improving and refining existing methods, in tandem with making them more cost effective and obtaining necessary authorizations for use. The open and growing Epidemic Response Quest community at humanitrack.org will continue to monitor the current global state of testing solutions (we currently have 273 molecular and 496 serological solutions in our open database) and provide the resources for this, identify the areas for improvement, and bring to the surface the future solutions and ideas that bring us closer to ideal testing of COVID-19.
Please come join our Quest and take action to improve our database, overview, understanding, and roadmaps so the world can align on what can be done to battle COVID-19 and future epidemics!
1. FDA. Accelerated Emergency Use Authorization (EUA) Summary Covid-19 RT-PCR Test (Laboratory Corporation Of America).
2. Kile Green, Amanda Winter, Rachel Dickinson, Sara Graziadio, Robert Wolff, Susan Mallett, A. Joy Allen. What tests could potentially be used for the screening, diagnosis and monitoring of COVID-19 and what are their advantages and disadvantages? . Centre for Evidence-Based Medicine. [Online] April 2020. https://www.cebm.net/covid-19/what-tests-could-potentially-be-used-for-the-screening-diagnosis-and-monitoring-of-covid-19-and-what-are-their-advantages-and-disadvantages/
3. COVID-19 tests: how they work and what’s in development. The Conversation. [Online] https://theconversation.com/covid-19-tests-how-they-work-and-whats-in-development-134479
4. An overview of the rapid test situation for COVID-19 diagnosis in the EU/EEA. European Center for Disease Prevention and Control.
5. Serology-based tests for COVID-19. Johns Hopkins Bloomberg School of Public Health: Center for Health Security. [Online] https://www.centerforhealthsecurity.org/resources/COVID-19/serology/Serology-based-tests-for-COVID-19.html#sec1
6. New Rutgers Saliva Test for Coronavirus Gets FDA Approval. Rutgers University. [Online] https://www.rutgers.edu/news/new-rutgers-saliva-test-coronavirus-gets-fda-approval
7. Digital spectrophotometry to detect COVID-19 or antibodies from saliva sample. Copenhagen Nanosystems ApS. [Online] https://cphnano.com/nanocuvette-sars-cov-2/
8. AI app can detect coronavirus from the sound of cough. Neuroscience News. [Online] https://neurosciencenews.com/ai-cough-coronavirus-16145/
9. CDC Laboratory Testing Capacity. US CDC. [Online] https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/testing-in-us.html
10. India's first paper-strip test for Covid-19. CSIR. [Online] https://www.livemint.com/news/india/india-s-first-paper-strip-test-for-covid-19-csir-lab-makes-a-breakthrough-11585832200999.html