Updated: FDA smooths the path for COVID screening tests
Editor’s note: This story has been updated to include remarks and perspective from an FDA Town Hall for test developers.At the one-year mark of the public health emergency of the pandemic, the US Food and Drug Administration (FDA) is providing a smoother road to the authorization of COVID-19 tests to screen asymptomatic individuals.
On Tuesday, FDA issued a fact sheet for those who are interested in setting up screening programs, an update to its FAQ document about COVID-19 testing, and a supplemental template for emergency use authorization (EUA) for COVID-19 diagnostic tests.
By issuing the supplemental template, FDA is offering “a streamlined path to emergency use authorization for these important screening tools,” according to a joint statement from Jeffrey Shuren, MD, director of FDA’s Center for Devices and Radiological Health (CDRH), and Timothy Stenzel, MD, PhD, director of the Office of In Vitro Diagnostics at CDRH.
In a departure from usual practice, FDA, “in certain circumstances,” is permitting authorization of a point-of-care or at-home test for use in asymptomatic individuals without the need for validation in that population. “The FDA believes that evidence of a test’s strong performance in symptomatic patients combined with serial testing can mitigate the risk of false results when testing asymptomatic individuals,” wrote Shuren and Stenzel.
Some points regarding the anticipated use of tests authorized under the template were clarified Wednesday during the weekly town hall held by CDRH for COVID-19 test developers. Stenzel explained that though this new template is for tests meant to be used serially in asymptomatic individuals, tests authorized through this template are to be used in serial screening “to make individual patient decisions,” rather than surveillance.
“We are very interested in home use” of tests for serial screening, said Stenzel, adding that both prescription and over-the-counter tests can be authorized via the template. To date, FDA has not received any EUA submissions of tests for serial testing.
The idea behind serial testing, he added, is to overcome lower sensitivity of some antigen tests by conducting repeat testing over a period of days. A comparison of this approach against more sensitive molecular testing revealed that a serial strategy “significantly mitigated the risk of false testing” via antigen tests, helping formulate CDRH’s approach.
Stenzel said that test developers should know that FDA is looking for performance sensitivity of at least 80% in these antigen tests meant for serial use, with the lower bound of the 95% confidence interval not dipping below 70%.
No test authorizations will automatically be changed because of FDA’s new approach to serial screening, clarified Stenzel. Developers must still use the supplemental template if they wish to seek an EUA for use in serial screening, and all other COVID-19 test EUA pathways still remain open, he said.
FDA sees the template and the streamlined path for test developers as a way to support the serial testing strategy recommended by the US Centers for Disease Control and Prevention (CDC). As noted by Stenzel and Shuren, CDC “recommends serial testing at least once per week” along with other mitigation measures to reduce transmission of COVID-19 during the pandemic.
“Serial testing 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,” wrote the FDA officials.
By preserving the idea that serial screening test strategies are still used in individual patient situations, FDA is allowing broad screening of asymptomatic populations without crossing over a regulatory threshold. An answer to a June 2020 question on the FAQ on uses of COVID-19 tests reads, “The FDA does not generally regulate the use of a test for surveillance purposes, such as determining the prevalence of acute infections in a population.”
In the same set of FAQs, FDA elaborated on its stance regarding screening for COVID-19 as of November 2020. “The FDA recognizes that the CDC has issued guidance relating to screening and that organizations may want to conduct screening of asymptomatic individuals as part of a strategy to assure the safety of their employees, patients, students, and others,” wrote the agency. At that time, FDA encouraged the use of highly sensitive tests for screening, and encouraged developers interested in using less-sensitive tests to discuss alternate strategies, such as serial testing, with the agency.
The new template can be used in development of molecular and antigen tests alike; intended uses can be serial testing programs or at-home testing designed to be conducted in a serial manner in asymptomatic individuals without known COVID-19 exposure.
The template can be used for tests intended to be used in a broad range of venues, ranging from the laboratory to the clinic, to the home, and even to “non-traditional” sites such as sporting venues, airports, and schools.