It has been two years since the COVID-19 virus began. Humans have invented new vaccines and virus technology to survive the war against this virus. At the same time, new variants of the virus are being spread and detected. In Korea, the daily number of confirmed cases of the virus was on the rise until the middle of March, when on March 16th, the highest number of confirmed cases was 621,328. As the number exploded due to the fast spread of the Omicron variant, the health care system could not keep up with the demand for only PCR tests . Therefore, the government and the Ministry of Health and Welfare decided to introduce self-test kits and rapid antigen tests to the public.

Types of COVID-19 Tests

A Real-Time PCR Test is a method of collecting samples by inserting a cotton swab deep into the nose or the back of the throat. It is known as the most accurate way among the various COVID-19 virus tests currently being used. After extracting RNA from the sample, this RNA is amplified. If there are two or more types of genes that have the same characteristics as the COVID-19 virus, the result is positive. However, there is a disadvantage to this test in that the test can be judged as negative if there are not enough cells in the sample.

The RT-LAMP Test is different because saliva is used in the test instead of the nose or throat samples used in PCR tests. If saliva is being used, the number of tests can be greatly increased because the tests results are returned quicker. Real-Time PCR Tests take six hours for results, while the RT-LAMP Test results come in less than an hour. Also, because the saliva is usually held at temperatures between 60~65℃, DNA can be amplified without expensive equipment. However, the big problem with this test is that it’s accuracy and sample sensitivity is lower than PCR tests.

How Does A Self-Test Kit and Rapid Antigen Test Work?

There are two types of kits that are being used for a rapid antigen test. The ‘Standard Q COVID-19 Ag’ product, common for professional use, collects samples from a nasopharyngeal smear (back of the nose and throat). The ‘Standard Q COVID-19 Ag Home Test’ product collects samples from a patients’ nasal discharge. This test kit can be easily found at pharmacies and convenience stores. Currently, rapid antigen tests are available at temporary screening clinics, public health centers, and hospitals. Although the advantage of this test is being able to conduct a test quickly, there is a disadvantage that its accuracy is lower than the two test types mentioned before.

A rapid antigen test uses the immunochromatography method. This is combination of immune response(antigen-antibody reaction) and a chromatography technique. When users open the kit, there will be a cotton swab, extraction tube, and test strip.

First, take the sample from your nose with a cotton swab and put this swab into the extraction tube to dilute it. If the analyte in the extraction tube is dropped onto the test strip kit, it flows to the other side. At this time, the analyte is combined with the labeled antibody on the strip and forms the analyte-labeled antibody complex.

As the analyte-labeled antibody complex continues to spread, it is combined with the primary antibody on the test line. This is called a sandwich complex, because it consists of three layers: labeled antibody, analyte, and primary antibody.

After forming the sandwich complex, the remaining analyte-labeled antibody complex binds to a secondary antibody on the control line. This control line is used to determine if the patient is positive or negative. If lines appear on both the test and control line, the test result is positive.

COVID-19 related public policies are changing over time. Recently, oral medicines are being introduced, the level of social distancing is being changed, and not wearing masks anymore are being considered. Please refer to the official announcements and news from the government and public health agencies. Hope everyone, including you who is reading this article, will live a safe life while following the correct quarantine rules.

(Source) Korean Government Briefing Official Website, https://www.korea.kr/special/policyFocusView.do?newsId=148898582&pkgId=49500742

Kim Youngwoo  kyeryoong@gmail.com

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