Some rapid antigen tests may not be able to detect the omicron COVID-19 variant effectively enough, according to Anthony Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases. “We’re getting preliminary information that not all of the [rapid] diagnostic tests will be accurate with omicron,” Dr. Fauci said in a virtual conversation with the Chamber of Commerce Foundation on Thursday.
That’s a problem, as rapid tests have been a significant—though imperfect—tool for detecting the SARS-CoV-2 virus. “Some, and many of the commonly used ones, appear to pick up and detect omicron quite well,” Dr. Fauci said. “We’re in the process of doing large screening to determine which of these antigen point-of-care rapid tests still maintain their accuracy of diagnosis. But clearly, there are some that do. We’re trying to find out those that don’t reflect an accurate result. And if we do, make sure that those tests are not used to diagnose omicron.”
Even at their best, rapid antigen tests haven’t been as accurate as polymerase chain reaction (PCR) tests, which are the gold standard for diagnosing COVID-19, as SELF has reported. According to a Cochrane review of 64 studies and more than 24,000 testing samples, rapid antigen tests managed to detect COVID-19 in 72% of symptomatic COVID-19 cases pre-omicron. In positive people without symptoms, they were only about 58% accurate. On the other hand, PCR tests are generally estimated to be around 98% accurate at detecting COVID-19 infections when used correctly. But rapid tests can come back in as little as 15 minutes at home, where PCR tests must be sent to a lab and take a few hours at minimum for results—and often take days.
Another major blow is that omicron has significantly reduced the effectiveness of monoclonal antibodies, one of few COVID-19 treatments. Monoclonal antibodies are lab-made antibodies delivered intravenously to high-risk people who have tested positive for COVID-19 or been in close contact with someone who has tested positive, per the U.S. Department of Health and Human Services. “When you look at the rather large number of mutations on the omicron variant, it is predictive and has shown in reality to evade certain immune parameters, such as monoclonal antibodies, many of which are no longer effective against this virus,” Dr. Fauci said.
The omicron variant has over 50 mutations from the original virus, including more than 30 on its spike protein, which helps the virus enter our cells, as SELF has explained. Many antibodies we generate from vaccination and infection (and most of the lab-made monoclonal antibodies) target these spike proteins—so when they change, it can make immunity and antibody treatments less effective.
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So, what does all of this mean if you were hoping rapid tests could be a core part of your protection strategy during holiday travel or gatherings? According to public health experts, they still can be.
“Folks will travel, see family/friends this holiday season,” Ashish K. Jha, M.D., MPH, dean of the Brown University School of Public Health, wrote on Twitter. “Use of rapid tests can make things safer.”
The Centers for Disease Control and Prevention (CDC) specifically recommends considering rapid testing before getting together indoors with anyone you don’t live with. But that shouldn’t be the only precaution you take.
“Ugh. Omicron is bad news. Get vaccinated if you haven’t been yet. Get boosted if you’re eligible. Wear masks. Avoid crowds. Ventilate if you can. Rapid test if available. Stay home if you don’t feel well,” Angela Rasmussen, Ph.D., virologist at Georgetown University Center for Global Health Science and Security, wrote on Twitter. And, importantly, she ended with a reminder that individual and community health very much go hand in hand during this pandemic: “Advocate for global vaccine equity. We have the tools. We must use them.”
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Source: SELF
