COVID PCR Testing Can be Fast—and It’s More Accurate than Rapid Antigen Tests

In February 2022, the state of Utah called an abrupt halt to the use of a rapid antigen test for COVID-19 at state-run testing sites. The test Utah was using turned out to have lower-than-expected sensitivity, meaning it was returning too many false-negative results.¹

The Utah Department of Health (UDOH) compared results from nearly 18,000 people who received the rapid antigen test and a PCR test on the same day. The analysis found that more than half of those who tested positive by PCR simultaneously tested negative by the rapid antigen test. UDOH noted that “this was true even for people who reported COVID-like symptoms.”¹

“While rapid antigen tests are known to be less likely to identify a positive individual, the difference identified in this analysis was higher than expected,” UDOH explained in a statement.¹

Testing Guidance

In addition to the known challenges with the sensitivity of rapid antigen testing for COVID-19, the FDA has indicated that such tests may have further reduced sensitivity for detecting the Omicron variant. “Early data suggests that antigen tests do detect the omicron variant but may have reduced sensitivity,” the FDA reported in December 2021.²

Because of the reduced sensitivity of rapid antigen tests, the FDA recommends follow-up molecular testing in some cases: “Antigen tests are generally less sensitive and less likely to pick up very early infections compared to molecular tests. In following the FDA’s long-standing rapid test recommendations, if a person tests negative with an antigen test but is suspected of having COVID-19, such as experiencing symptoms or have a high likelihood of infection due to exposure, follow-up molecular testing is important for determining a COVID-19 infection.”²

In fact, the CDC notes that, “In most circumstances, the manufacturers’ instructions for use of antigen tests indicate that negative test results should be considered ‘presumptive,’ meaning that they are preliminary results.”³

The CDC calls nucleic acid amplification tests (NAATs), the “gold standard for clinical diagnostic detection of SARS-CoV-2,” adding that it may be necessary “to confirm an antigen test result with a laboratory-based NAAT, especially if the result of the antigen test is inconsistent with the clinical context.”³

Multiplex PCR Testing

Rapid antigen tests are just that—rapid. That’s the upside that balances out the downside of reduced sensitivity. Laboratory NAAT tests, the CDC’s “gold standard,” can take days to return results.⁴

However, the BIOFIRE^® Respiratory 2.1 (RP2.1) Panel is a polymerase chain reaction (PCR) test—a type of NAAT—that offers results in about 45 minutes and features sensitivity of 98.4% for SARS-CoV-2.⁵ Intended for use with patients suspected of COVID-19, the BIOFIRE^® Respiratory 2.1-EZ (RP2.1-EZ) Panel (EUA)* also detects SARS-CoV-2 with a high degree of sensitivity and can be used in an outpatient setting, providing a fast and accurate option for urgent care clinics, family physicians, and other frontline facilities.

These respiratory PCR panels have another benefit: they take a syndromic approach to respiratory testing. While testing for COVID-19, they also test for several other respiratory targets. Fast and accurate answers on a COVID PCR test are great—but what if the patient is symptomatic and tests negative for COVID-19? Syndromic testing gives clinicians answers on a broad menu of targets with one easy multiplex PCR test. The BioFire RP2.1-EZ Panel (EUA) detects 19 relevant targets, including but not limited to SARS-CoV-2, influenza, and respiratory syncytial virus.

Several respiratory pathogens have been circulating during the 2021-2022 respiratory season, not just SARS-CoV-2. Influenza A has been active, as well as respiratory syncytial virus and human rhinovirus/enterovirus.⁶

Syndromic testing is a valuable approach for frontline testing for COVID-19. The BioFire RP2.1 Panel and BioFire RP2.1-EZ Panel (EUA) offer results in just 45 minutes, and the panels are easy to run and only require 2 minutes of hands-on time. These respiratory PCR tests are considerably more accurate than rapid antigen tests. And, importantly, the syndromic approach provides results on a comprehensive menu, giving clinicians—and their patients—solid answers even when the tests are negative for SARS-CoV-2.

Syndromic Testing

The typical symptoms of COVID-19 are similar to, and even overlap with, many other respiratory infections like influenza or the common cold. Multiplex PCR testing with BioFire’s respiratory solutions helps remove guesswork by combining several possible targets into one quick test. BioFire’s real-time PCR system is more sensitive than rapid antigen testing, and a fast COVID PCR test can help get patients the answers they need without requiring additional testing.

COVID PCR SOLUTIONS HERE

Learn More about Testing for COVID-19 and the Syndromic Approach

References:

UDOH. UDOH to temporarily pause use of on-site rapid tests at state testing sites. Accessed on 28 Feb 2022. Retrieved from: https://health.utah.gov/featured-news/udoh-to-temporarily-pause-use-of-on-site-rapid-tests-at-state-testing-sites
FDA. Omicron Variant: Impact on Antigen Diagnostic Tests. Accessed on 28 Feb 2022. Retrieved from: https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/sars-cov-2-viral-mutations-impact-covid-19-tests?utm_medium=email&utm_source=govdelivery#omicronvariantimpact
CDC. Guidance for Antigen Testing for SARS-CoV-2 for Healthcare Providers Testing Individuals in the Community. Accessed on 09 March 2022. Retrieved from: https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antigen-tests-guidelines.html
CDC. COVID-19 Testing: What You Need to Know. Accessed on 09 Mar 2022. Retrieved from: https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html#:~:text=COVID%2D19%20tests%20can%20detect,the%20time%20of%20the%20test.
Overall performance based on prospective SARS-COV-2 clinical study for the BioFire® Respiratory 2.1 Panel in comparison to 3 EUA tests.
BioFire^® Syndromic Trends.

*This product has not been FDA cleared or approved, but has been authorized for emergency use by FDA under an EUA for use by authorized laboratories;
This product has been authorized only for the detection and differentiation of nucleic acid of SARS-CoV-2 from multiple respiratory viral and bacterial organisms; and,
The emergency use of this product is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostics for detection and/or diagnosis of COVID-19 under Section 564(b)(1) of the Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 360bbb-3(b)(1), unless the declaration is terminated or authorization is revoked sooner.

COVID PCR Testing Can be Fast—and It’s More Accurate than Rapid Antigen Tests

Testing Guidance

Multiplex PCR Testing

Syndromic Testing

Learn More about Testing for COVID-19 and the Syndromic Approach

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