Using Rapid Antigen Tests To Fight SARS-CoV-2
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Testing continues to be a priority in the global response to the COVID-19 pandemic, with many countries implementing large-scale screening programs using rapid antigen tests, in a bid to identify asymptomatic individuals and break chains of transmission.
Technology Networks recently interviewed Anthony V. Lemmo, to learn how rapid antigen tests work, how they compare to PCR tests and how they can be used to help slow the spread of SARS-CoV-2. Anthony is CEO and president of BioDot, a company that manufactures the dispensing technology currently used by more than 80 diagnostics manufacturers worldwide to make COVID-19 antigen tests.
Anna MacDonald (AM): Could you give us an overview of how COVID-19 rapid antigen tests work?
Anthony V. Lemmo (AL): Antigen tests are used to detect the presence of the proteins that exist on the surface of the virus. These proteins, or antigens, are the molecules that trigger a body’s immune response and the production of antibodies that can fight the virus. The rapid COVID-19 antigen tests are a lateral flow test – the same format as a home pregnancy test – that includes a test strip containing SARS-CoV-2 antibodies. First, the sample is collected from the patient, usually from a nasal or throat swab, and placed in a solution known as an extraction buffer that breaks the cells open and releases specific viral proteins. This mixture is placed on the lateral flow test containing the antibodies which will bind to the proteins. A positive result will trigger a visual change on the strip.
AM: How do rapid antigen tests compare with molecular tests such as PCR?
AL: Molecular tests such as PCR tests are used to detect genetic material rather than proteins. For a PCR test, the same sample swab is sent to a lab where technicians use reagents, lab equipment and a time-consuming process to convert the virus's RNA into DNA, which is replicated to make millions of copies. This makes it possible to identify the organism. This process is typically only used on one sample at a time and can take hours, but it is highly accurate.
AM: In what ways could rapid antigen tests be used to help slow the spread of SARS-CoV-2?
AL: Because rapid antigen tests can be mass produced and the test results only take around 30 minutes, it is possible to test many more people than with PCR alone, an important tool for a pandemic-fighting effort. The industry has the capacity to test large groups of people with rapid antigen tests, such as at universities or workplaces. By testing different populations en masse, we can catch more positive cases of COVID-19 even when people are asymptomatic, or for people that don’t realize they’ve been exposed and therefore wouldn’t seek out a PCR test.
It’s also important to consider how both PCR and rapid antigen testing capacity can be utilized together to slow the spread of COVID-19. Suspected cases can be tested quickly with the antigen tests. Because false positives are rare, a positive antigen test result can be considered confirmatory. If it comes back negative but the patient in question has been at high-risk for exposure, a PCR test could then be done to ensure they are in fact negative.
AM: Some rapid antigen tests require prescriptions, while others do not. What are the reasons for this?
AL: COVID tests are an important epidemiological tool, and while the technology is well suited to at-home use, it’s important that test results are recorded and reported to the appropriate health agencies so that they can conduct contact tracing or identify outbreaks in a certain region. To fight the virus, we need to understand it and know where it is. Requiring a prescription is an assurance that there is a process in place to report positive test results, whether that be through an app or by giving the result to the prescribing physician.
AM: How are rapid antigen tests made? Can you give us some insights into how BioDot is helping to scale-up test production?
AL: High-volume, high-quality manufacturing of rapid diagnostic tests requires specialized equipment capable of precision alignment of materials, accurate fluid dispensing and assembly technologies, in addition to skilled operators trained in the manufacturing of these tests. Test quality is directly impacted by the design of devices, choice of raw materials and reagents and the manufacturing process.
BioDot, the global leader in ultra-low volume, non-contact quantitative fluid dispensing systems, dispenses highly precise volumes of specialized reagents for detecting COVID-19 and antibodies. The company remains committed to accelerating manufacturing of its systems to support diagnostics manufacturers around the world. These systems are enabling the production of millions of COVID-19 tests.
Anthony Lemmo, PhD, was speaking to Anna MacDonald, Science Writer for Technology Networks.