The U.S. FDA has issued an emergency use authorization (EUA) for an antigen test for the SARS-CoV-2 virus from Quidel Corp., of San Diego, that is more readily deployed than other diagnostic tests for the pathogen.

Quidel’s offering can be used at the point of care (POC) and as a lab test. Labs practicing the Sofia test for this pathogen must qualify for moderate- and high-complexity testing under the Clinical Laboratory Improvement Amendments (CLIA) of 1988, while the POC version must be practiced under a CLIA certificate of waiver.

The company said that the Sofia test relies on nasal or nasopharyngeal specimens and can be analyzed on automated or manual analyzers. Health care professionals can obtain the kits from any one of several sources, including Cardinal Health.

The FDA’s action comes after criticism dogged its approach to testing regimes in the early days of the COVID-19 pandemic. It subsequently has moved aggressively to give test developers rapid access to the U.S. market.

For its part, Quidel has high hopes for the test. “The EUA for our Sofia 2 SARS Antigen FIA allows us to arm our health care workers and first responders with a frontline solution for COVID-19 diagnosis, accelerating the time to diagnosis and potential treatment of COVID-19 for the patient.” said Doug Bryant, president and CEO of Quidel.

Still, the agency acknowledged that a negative finding with the Quidel test may require confirmatory molecular testing prior to treatment, but it also promised that more antigen tests will be available soon.

Diagnostic tests – each with their ‘own unique role’

Molecular tests for viral RNA, typically polymerase chain reaction (PCR) tests, were the first diagnostic options included in the FDA’s EUA program. The agency now has said that each type of diagnostic test “has its own unique role in the fight against this virus.” Despite the rate of false negatives attributed to molecular testing, this antigen test is said to be less sensitive than PCR testing. However, the Quidel test is credited with offering a high degree of specificity, and the FDA said a negative result for this test may require a PCR or other molecular test “prior to making treatment decisions or to prevent the possible spread of the virus.”

The agency noted that tests for the viral antigen “are also important in the overall response” to the pandemic due to the lower cost incurred compared with PCR. Antigen testing may be available for “millions of Americans per day” once multiple offerings are on the market, the FDA said, a volume achieved in part by the relatively simple design of the related test instruments. As a result, antigen testing may aid in the effort to track infection rates in a manner that more closely resembles real-time tracking.

FDA Commissioner Stephen Hahn and Jeff Shuren, director of the Center for Devices and Radiological Health, advised that “this is just the first antigen test to be authorized.” To that end, developers have another resource, with the agency providing a May 11 update that gives a template for antigen testing. Another feature of the update is a revised policy for testing, which overwrites the May 4 policy that imposed the 10-day turnaround for serological testing. The section dealing with antigen testing states that clinical agreement should be established on human specimens, and notes that the template offers specifics on issues such as studies of reagent stability and methods for determining the test’s limits of detection.

Investors appeared to be very excited about the company’s news, sending Quidel’s shares (NASDAQ:QDEL) soaring to $208.95, up $50.35, or 31.75%, at market close May 11.

Former FDA Commissioner Scott Gottlieb described the advent of this test for COVID-19 as “a real game-changer,” in part because the machines used to process the samples already are installed in thousands of doctor’s offices across the U.S.

BD said to be up next with antigen testing

William Blair’s Brian Weinstein has not been shy in saying the Quidel offering has great potential.

“If successful in obtaining EUA [emergency use authorization] for this test, Quidel would play a major part in this and, along with Becton Dickinson[, which] is the other rapid antigen player, begin to democratize testing and provide a rapid, scalable solution that complements the centralized testing solutions that have emerged from the likes of Abbott, Hologic, Luminex, Qiagen, and others,” he said previously.

His enthusiasm continued in the wake of the FDA’s latest move. “Overall, we believe this is a landmark approval that should make a big dent in testing frontline workers and also lead to revenue and cash flow for Quidel that is astonishing,” he wrote in a May 11 note.

He noted that Quidel has an installed base of 36,000 instruments in the U.S., which are linked to a cloud-based tracking component. The cloud link should assist in identifying new outbreaks, and the news “should drive a massive inflection” in the related earnings before interest, taxes, depreciation and amortization (EBITDA). He also noted that Franklin Lakes, N.J.-based Becton, Dickinson & Co. “is on the clock” to get its antigen test to market.

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