A tweet falsely states that rapid tests are not accurate

As the COVID-19 pandemic emerged in 2020, there were few tests available but within months several types of tests were introduced and soon became widely available. Testing is an important tool in helping contain COVID outbreaks but a great deal of misinformation has spread online about the accuracy of the different types of tests available.

On May 8, 2020, the U.S. Food and Drug Administration issued the first emergency use authorization (EUA) for a COVID-19 rapid antigen test. The Emergency Use Authorization was issued to Quidel Corporation for the Sofia 2 SARS Antigen FIA. This came several months after the polymerase chain reaction (PCR) tests rolled out. According to the FDA, “PCR tests can be incredibly accurate, but running the tests and analyzing the results can take time. One of the main advantages of an antigen test is the speed of the test, which can provide results in minutes.” 

In an interview, Dr. Wilbur Lam, professor of pediatrics and biomedical engineering at Emory University and Georgia Institute of Technology, stated that there are “two categories of COVID-19 tests right now. One is the rapid test which as the name implies [is] easy to do…fairly inexpensive, and…many of them have been authorized for home use.”

He explained that the science behind rapid antigen tests isn’t new, “it’s actually technology that’s been around for decades. It’s very similar to the technology that home pregnancy tests [use]…PCR has been around for many decades as well…[but] because of the way PCR works it usually requires a more complex gadget and usually it is based in hospitals.” Lam went on to explain the sensitivity of the PCR test, stating that “the difference in utility in terms of how you use them is PCR testing tends to be a little bit more sensitive…it can detect a lower amount, a much less concentrated amount of virus than a rapid test.” 

However this does not make the rapid test any less of an important tool, and individuals can use serial testing, which is testing at different points in time, to “mitigate the slightly decreased sensitivity of the rapid tests,” Dr. Lam explained. 

Dr. Lam’s observation on serial testing is shared by author Victoria T. Chu, MD, MPH et al., in a scholarly article in which the authors studied 225 adults and children COVID testing results utilizing home antigen tests versus PCR tests. According to the authors, “symptomatic individuals with an initial negative home antigen test result for SARS-CoV-2 infection should test again 1 to 2 days later because test sensitivity peaked several days after illness onset and improved with repeated testing.” [Emphasis added.] 

The practical importance of the rapid tests are critical. According to author Monica Pena et al., in the article “Performance of SARS-CoV-2 rapid antigen test compared with real-time RT-PCR in asymptomatic individuals” rapid antigen tests “might have a significant impact on the identification of asymptomatic carriers in areas that lack suitable laboratories to perform” more sensitive PCR tests which would also take far longer. The authors concluded that, given the “fast test results” and ability to get results for individuals not exhibiting COVID-19 symptoms, rapid tests “might have a significant role in COVID-19 screening, testing and contact tracing strategies to control the COVID-19 pandemic.”   

The importance of COVID-19 rapid antigen tests cannot be overstated. “Before the pandemic there wasn’t really much thought that infectious diseases could be tested at home,” Dr. Lam said. “But what we’ve learned with the pandemic is that with accessibility and the capability for the public to have access to all these tests that…it can actually save lives.”

If you wish to obtain an at-home test, you can go to one of the city-wide pick-up sites or visit www.covid.gov/tests and order a test by mail. For overall information regarding testing, please go to www1.nyc.gov/site/doh/covid/covid-19-testing.page. These and other resources can also be accessed on the AmNews COVID-19 page: www.amsterdamnews.com/covid/

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