Can Rapid Antigen Tests Detect The Omicron Variant?
With the Omicron variant, the SARS-CoV-2 pandemic has started a new era. It is more infectious but milder. According to WHO, Omicron to infect more than half of Europe’s population in a very short time interval. This situation will come with its consequences such as the fact that most people become asymptomatic carriers and governments need an increased number of tests to screen and control the spread of the SARS-CoV-2. Due to the costs of and time needed for the RT-PCR test, authorities seek an alternative in these times. Rapid Antigen Tests (RATs) have been encouraged as an alternative, however, their sufficiency and efficiency to detect the omicron variant are under discussion among people. In this article, the efficiency and sufficiency of RATs to detect omicron will be examined in detail.
Symptoms of the Variant Omicron
Omicron comes with respectively milder symptoms that are like the typical flu. Crucial symptoms such as the loss of taste and smell that declare SARS-CoV-2 infections are becoming less and less common with Omicron. While diminishing the influence of taste and smell loss, cold-like symptoms such as sore throats, runny noses, and sneezing are seen more frequently. Milder symptoms paired with higher infection probability increase the risk of asymptomatic transmission. Rapid antigen tests are being integrated into our daily lives more and more every day. As the infected patient will have the disease with symptoms that will not interfere with his or her daily life, noticing the danger and taking actions will be harder than before. To overcome this risk, regular testing is essential. However, traditional diagnostic tests such as RT-PCR become an economic burden for both individuals and governments. The use of this time-consuming, expensive method has subsided with the rise of using rapid tests. Individuals can continue their social and daily lives, which were impacted by SARS-CoV-2, in a safer way, with rapid diagnostic tests, where they can get results easily and in a short time, at home, at work, or in other areas where they need it.
Mutations of Omicron Variant
With the arrival of the Omicron variant, the question arises whether rapid diagnostic tests can detect this variant. It is seen that the resulting mutations reduce the sensitivity of the rapid tests rather than preventing their detection. Commonly, nucleoproteins or nucleocapsid proteins are used as target proteins in the detection of SARS-CoV-2 with rapid antigen tests. The variant Omicron carries approximately 30 mutations. Studies have shown that one of the main variables in this mutation type includes a deletion in the S gene which probably affects PCR testing rather than antigen rapid testing for COVID-19. On the other side, a deletion in Del31-33 occurs in the Omicron variant nucleocapsid protein. It has been observed that while this deletion does not prevent detection in rapid diagnosis kits, it reduces sensitivity values. Even though the variability in sensitivity and probability of false-negative results raise concerns, constant developments and studies will allow preventing sensitivity values from being affected by variants. Altogether rapid diagnostic tests are still an important factor keeping the transmission under control.
The Question
High number of mutations and changes in the influences and frequencies of symptoms faced with the Omicron variant. These phenomena bring concerns with them: How we can control the spread? The answer was easy, and it was to increase the number of tests between citizens. However, real-time polymerase chain reaction (RT-PCR) testing was and still is an expensive and time requiring method. RT-PCR tests were needed to be replaced by an alternative, and we had rapid antigen tests. The methodology behind how the rapid antigen tests work has not yet been fully understood by people. This is the main reason why people keep asking if rapid antigen tests are sufficient to detect Omicron or not. In the following part the methodology of rapid antigen tests will be examined and discussed.
The Methodology behind Rapid Antigen Tests
Rapid antigen tests are point-of-care diagnostic tools. They are usually used for the screening of the viral antigen indicating the presence of the virus of interest. Rapid antigen tests have been a part of our lives for a while. However, with the SARS-CoV-2, we have been more familiar with these lateral flow immunoassay tools. Rapid antigen tests are portable, single use and fast result providing tools that eliminate the requirement of laboratory testing. These characteristics make them cost-effective and a strong alternative to laboratory tests such as RT-PCR.
The principle behind the mechanism of action of rapid antigen testing used for SARS-CoV-2 detection is simple. If the collected sample contains SARS-CoV-2 antigens during testing, these antigens will adhere to the nanoparticles coated with the anti-SARS-CoV-2 antibody contained in the reactive test strip. This reaction causes a colored line to appear on the test cassette, indicating the presence of COVID-19-specific antigen in the sample, with a positive result.
Antigens are the proteins or parts of the proteins serving as target to selected antibody in the reactive test strip. They can range from spike proteins to nucleocapsid proteins. In the case of the Omicron variant, most of the mutations are carried on the spike protein. This can decrease the sensitivity or result in non-functional tests for the rapid antigen tests using spike protein of SARS-CoV-2 as target. However, those using nucleocapsid protein as a target are less likely to be influenced by the mutations in terms of sensitivity and functionality.
Conclusion
The Omicron variant changes the game of SARS-CoV-2 pandemic. Features specific to this variant raise concerns about the spread of the SARS-CoV-2. As mentioned above, its mutations cause the Omicron variant to be not only more infectious, but they also significantly increase the number of asymptomatic cases due to its mutations. Due to the high number of patients experiencing mild symptoms or no symptoms at all, it has become easier and more common than ever for people to dismiss their symptoms, confuse them with the common cold, and unknowingly transmit the virus. The emergence of the Omicron variant has also raised the question of whether rapid antigen tests can reliably detect the Omicron variant. Indeed, as the mutations observed in the Omicron variant are predominantly carried on the spike protein, rapid antigen test kits that target the SARS-CoV-2 spike protein may have limited sensitivity and accuracy. However, the sensitivity and accuracy of rapid antigen tests that target SARS-CoV-2 nucleocapsid protein are less likely to be curbed by the mutations. Unlike those targeting SARS-CoV-2 spike protein, currently there is no scientific evidence demonstrating that these tests fail to detect SARS-CoV-2 infections.
Altogether, it might be safe to claim that some forms of rapid antigen testing are still effective and convenient tools in screening the Omicron variant. RapidFor ™ SARS-CoV-2 Rapid Antigen Test Kit recognizes the nucleocapsid protein of SARS-CoV-2 by pairing the selected monoclonal antibody. As it uses the SARS-CoV-2 nucleocapsid protein, our test kit preserves its sensitivity, specificity, and overall accuracy against the Omicron variant. Combining accuracy, affordability, simplicity, and speed; RapidFor ™ SARS-CoV-2 Rapid Antigen Test Kit ensures reliable results for all in no time.
