SARS-CoV-2 Rapid Tests
SARS-CoV-2 testing has played an essential role in controlling the COVID-19 pandemic. Although testing capacity was initially limited in early 2020, expansion of rapid, point-of-care (POC) testing systems offered an opportunity to increase testing volume at reduced cost and decrease the turnaround time for results. POC tests such as lateral flow immunoassays, tests that detect the presence of SARS-CoV-2 surface antigens, might be less sensitive than the gold-standard real-time polymerase chain reaction (RT-PCR) but generally provide results in under 30 minutes and require use of shorter nasal swabs versus longer swabs which are often found to be uncomfortable.
We validated the operational and quality performance of various rapid tests in comparison to a RT-PCR assay. Although these tests were given emergency approval for use by the Food and Drug Administration (FDA), it was important to understand and evaluate how the tests performed in real-world testing settings in New York City. If the rapid tests met quality performance criteria and were adaptable to different testing locations with multiple test operators, we made the test available through the Test & Trace Corps community testing sites. Failure to meet these criteria resulted in the test being excluded from further evaluation and deployment. As of May 2021, rapid tests have been deployed at 18 Test & Trace sites and 40 mobile units across NYC, and over 110,000 tests have been performed.
An Operational Perspective on Testing
Operational considerations included testing time, staff training, affordability, and scalability. In NYC, a critical factor was physical space to store thousands of tests and reagents needed to conduct the tests. We preferred assays that did not require equipment and cold chain as they eliminated many logistical and space related concerns (security, temperature requirements, etc.). Furthermore, testing systems that didn’t require external equipment provided a high degree of flexibility, allowing for our teams to shift testing kits in real-time.
We also prioritized having consistent inventory of test kits, reagents, and supplies. A continuous dialogue with distributors was essential, as was the ability to make high-volume purchases whenever an opportunity presented itself. In parallel, we had to predict future test utilization and validate multiple tests so as not to be dependent on any one assay given the risk of supply shortages and changes in testing needs. Inventory of test kits was additionally managed so as to reduce wastage. With the rising popularity of rapid tests, another issue was competition with other high-volume purchasers. Supply chain bottlenecks and shortages could have potentially led to decreased access to testing and loss of trust in the communities we served.
Long-term Use and Monitoring
Rapid tests require validation across different settings, scenarios, and end-users to avoid inaccurate and invalid results as well as ongoing monitoring. Studies have shown that some COVID-19 POC tests show decreased performance depending on the test operator, as seen in the United Kingdom’s Innova evaluation.1 This highlights the importance of training and clear manufacturer instructions. Test & Trace staff who performed testing received ongoing training and competency monitoring to ensure consistent use and interpretation of these assays. Additionally, to ensure long-term success of rapid test deployment and use in the field, we monitored our testing program via performance metric data.
Looking Back and Looking Ahead
Recognizing the need to increase testing capacity, Test & Trace was uniquely positioned to evaluate and scale rapid testing options in real-time, bolstering our pandemic response efforts in a dense, urban environment. During this process, we learned of the numerous operational challenges associated with supply chain, procurement, finances, and logistics. We additionally recognized the implications and importance of long-term monitoring. Although findings from our evaluation are specific to the NYC Test & Trace testing infrastructure, we urge that rapid test validation be adapted for additional settings and used for future pandemic preparedness and response.
- Peto T. COVID-19: Rapid Antigen detection for SARS-CoV-2 by lateral flow assay: a national systematic evaluation for mass-testing. medRxiv. 2021Jan26.