Merely weeks after the World Health Organization declared Omicron as a SARS-CoV-2 variant of concern, this new variant has already caused exponential surges in cases worldwide. It put a massive burden on healthcare systems and changed various safety and testing protocols.
While scientists continuously understand this new variant and how its mutations contribute to its transmissibility and pathogenicity, there have been questions raised about the effectiveness of the rapid antigen test that plays a critical role in identifying infections.
Amid recent research and anecdotes suggesting that the test might be less sensitive to Omicron, many ask how reliable it is in detecting the new variant.
What is the Rapid Antigen Test?
Rapid antigen tests, also known as lateral flow tests, can detect the viral proteins of the SARS-CoV-2 virus through a nasopharyngeal and nose swab. This type of test is fast and simple and can deliver results in 15 minutes to an hour.
Rapid antigen tests are also primarily used in monitoring population-wide infection rates and can be performed at point-of-care. Unlike PCR tests, rapid antigen tests are less reliable with good specificity but only moderate sensitivity.
How Reliable is Rapid Antigen Test in Detecting Omicron?
Coronavirus tests that use lateral flow technology to determine the presence of antigens quickly became the most prominent way of detecting infections during the surge in cases due to the Omicron variant. Yet, reports regarding its reliability prompted discussion among scientists and public health experts if this test is quite effective at picking up cases of Omicron as it has been during the previous variants.
A small study conducted by researchers in the US found that the two widely-used rapid antigen tests, BinaxNOW and Quidel QuickVue, seemed to lag several days in the detection of Omicron cases. This was reported after many infected people continued to test negative despite receiving a positive result from a PCR test.
An earlier study by researchers in Switzerland posted as a preprint but still has not been peer-reviewed examined the performance of antigen tests on cultured viruses instead of samples provided by people. The study found that the tests were less sensitive to detecting Omicron.
Accordingly, the US Food and Drug Administration (FDA) said in late December that “early data suggests that antigen tests do detect the Omicron variant but may have reduced sensitivity.
On the other hand, the UK Health Security Agency tentatively concluded that lateral flow devices, used by the National Health Service, show comparable sensitivity to Omicron as to other variants, is also continuing to monitor their performance. You can also read more details here.
While continuous research is underway and it is still unclear whether rapid antigen tests are less effective at picking up Omicron cases, there are ways to ensure that these tests can produce results with greater accuracy:
- Rapid antigen tests are most accurate when an individual is symptomatic. It is advisable to wait a day or two into symptoms before using the test, as people turn symptomatic a day or so before they turn positive.
- If you are symptomatic but tested negative on the first test, wait a day or two, then take a test again. There is a good chance that after two days, the virus would have replicated; thus, your viral load will be high enough to give you a positive result.
- If you still test negative despite taking two rapid antigen tests and still experience symptoms, consider getting tested for the third time or using a PCR test.
A rapid antigen test can provide useful information and can detect Omicron variants. However, it is essential to keep in mind that false negatives can happen. For individuals who tested positive, whether it is their first or second test, immediately isolate.
Are you looking for a testing provider?
Harley Medic International is a government-approved testing provider and an expert in COVID-19 testing. They have many locations across the UK, ensuring that a testing centre is near you. Getting a test is as easy as booking online and finding their closest clinic. Visit their website harleymedic.co.uk to learn more.