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The COVID-19 pandemic has changed our approach to health and strengthened our sense of social responsibility. We quickly realized that each of us had a real impact on the coronavirus disease curve. The “I stay at home” campaign, the # SzczepimySię campaign, and now self-testing is a signal: I protect myself and others.
“Lifebuoy” in crisis …
Antigen tests in the course of the pandemic turned out to be a real revolution and changed the approach to the diagnosis of COVID-19 disease. Compared to molecular tests (RT-PCR * test), they are faster, cheaper and do not require specialized equipment.
These advantages determined the fact that on October 28, 2020, the European Commission recommended the use of rapid antigen tests as part of the European strategy for counteracting the COVID-19 pandemic [1]. A few days later, they were included in the new definition of COVID-19 diagnosis developed for the needs of epidemiological surveillance. Thanks to this, Polish medics gained a new weapon in the fight against the SARS-CoV-2 virus, which improved work in hospitals and other health care facilities.
In practice, this meant rapidly differentiating a virally infected patient from a non-infected patient. Additionally, rapid tests opened up access to tests for many more people and reduced the burden on diagnostic laboratories. So let’s take a closer look at how antigen tests work …
Antigen tests, which is what?
The whole test looks for viral proteins (antigens) that stimulate the body to produce antibodies against the virus. A typical antigen test begins with a swab from the back of the nose, throat or nasopharynx, and then the swab sample is mixed with a solution that “breaks down” the virus and releases its proteins. The mix is placed on a paper strip containing an antibody adapted to bind virus antigens. A positive test result is a fluorescent glow or a dark strip.
Importantly, antigen tests are characterized by high specificity **, which means that a positive test result confirms SARS-CoV-2 infection with a high probability. Unlike molecular tests, however, they are less sensitive ***, i.e. the ability to detect infected people after the tenth day from the onset of symptoms. This means that while the RT-PCR test shows infection, even when the patient has recovered and is no longer infected, quick tests allow you to focus on the most infectious people with high virus concentration in the body.
According to WHO recommendations, antigen tests for the detection of SARS-CoV-2 infections should meet the criteria of sensitivity ≥80% and specificity ≥97% in relation to genetic tests [2]. On November 14, 2020, the Main Board of the Polish Society of Epidemiologists and Doctors of Infectious Diseases determined which exact antigen tests available in the manufacturers’ offers meet the above-mentioned criteria [3]. First of all, the reports and publications of the results of tests carried out with the use of specific tests were assessed, and such antigen tests were rejected, the value of which was based solely on manufacturers’ declarations.
The conditions for rapid antigen tests allowing for use for diagnostic purposes in symptomatic patients in the acute phase of SARS-CoV-2 infection were met by three tests: Panbio ™ COVID-19 AG Rąpic Test Device (Abbott), Bioeasy 2019-nCoV Ag Fluorescence (Shenzhen Bioeasy Biotechnology) and Standard Q COVID-19Ag SD (Biosensor) / SARS-CoV-2 Rapid Antigen Test (Roche).
Home smear point?
Initially, antigen tests could be performed by healthcare professionals, but as early as March 2021 they became available to users, provided that they were placed on the market as self-testing devices and had a certificate issued by a notified body. In addition, their packaging (marking) and instructions for use must contain a clear wording about the purpose for self-testing, and next to the CE mark, the number of the notified body that has certified the test [4].
An example of a test that meets these conditions is SARS-CoV-2 Antigen Self Test Nasal, distributed by Roche Diagnostics Polska sp. Z oo, available from February 2021 on many European markets (Germany, the Netherlands, Switzerland, Slovakia), and from July also in Poland.
By following simple instructions, anyone in the 18-68 age group can do the home test with a painless nasal swab, not the nasopharynx, without special training or supervision by medical staff. We will know the result in just 15 minutes! Which de facto means identifying positive cases almost immediately and leads to increased protection and reduced transmission of the infection.
The test itself is non-invasive, simple and convenient. How to perform the test? After washing your hands thoroughly with soap and water or using a disinfectant, remove the swab from the packaging and …
The clinical performance of the SARS-CoV-2 Antigen Self Test Nasal, was measured in a comparative study with Roche’s highly sensitive reverse transcriptase polymerase chain reaction (RT-PCR) test using nasopharyngeal swab specimens as a comparator that is the gold standard for infection detection SARS-CoV-2. The results of the study showed that the relative sensitivity of SARS-CoV-2 Antigen Self Test Nasal was 91,1% (95% CI: 83.8% 95.8%, N = 101, with Ct ≤ 30, IFU v2 data) and the overall relative specificity – 99,6% (95% CI: 97.7% 100.0%) [5]. In another comparative, independent, self-test study in which patients followed written and illustrated instructions for self-sampling, testing, and reading, the majority (80,9%) of study participants found the procedures easy to perform [6].
You protect yourself and protect others
Are you wondering how the self-test can help us overcome the COVID-19 pandemic?
Let’s start with the fact that in addition to the previously used principles of prevention, i.e. keeping distance, disinfecting, wearing masks and vaccinations, they strengthen social security. The experience of other countries shows this – in Germany, self-testing tests are available in shops, pharmacies and on the Internet. According to the guidelines, they are used to ensure safety against “everyday situations”, i.e. family gatherings or going to the cinema or theater. In contrast, in the UK, self-monitoring tests are part of the national SARS-CoV-2 testing program. They are used, inter alia, for self-control in asymptomatic high school students, primary and secondary school employees, as well as in people living with them.
The list of advantages of having a self-test for SARS-CoV-2 infection in your home medicine cabinet is really long …
First, as we know, vaccination against COVID-19 protects us from severe disease and hospitalization, but not 100%. effectiveness against virus transmission, as discussed by Paweł Grzesiowski, MD, PhD.
We must not spread the word that vaccination closes the pandemic theme. Yes, patients vaccinated with two doses will not go to hospitals and will not die from COVID-19 disease. However, the virus, unfortunately, has a chance of continuing to transmit in people, including those who are vaccinated.
This shows that testing for coronavirus stays with us for a longer time, and in the event of alarming symptoms, a quick antigen test is the best and the shortest way to verify the infection.
Secondly, it is an excellent prevention tool in situations where the risk of coronavirus infection is high, i.e. when attending concerts or collective events, visiting a club or bar, or traveling by plane. Especially since the experiences from the previous stages of the pandemic show that asymptomatic cases of infection were one of the factors contributing to its development. Self-monitoring tests therefore respond to the so far unmet need for control in asymptomatic patients.
The exclusion of infection after exposure is of particular importance before close contact with people belonging to the risk group of severe COVID-19: the elderly and the chronically ill. The obtained positive result enables immediate measures to be taken to prevent transmission of the virus – isolation, tracing of contacts and medical consultation, during which the doctor will order an RT-PCR test if necessary.
As Paweł Grzesiowski, MD, PhD emphasizes:
The use of self-monitoring tests can be very useful in interrupting the transmission of infections in large clusters of people in closed rooms: in workplaces or educational institutions such as universities, schools, kindergartens and nurseries. Each employee can quickly check whether they are infected with the coronavirus in the event of symptoms. This can prevent the virus from entering such an environment. Self-monitoring tests can also increase the security of the organization of mass events, allowing extensive testing of participants before the event begins.
A new element of normality?
The COVID-19 pandemic has changed our lives irretrievably and in the light of reports of new variants of the coronavirus, it is clear that the “normality” we were used to no longer exists. Does that mean we have lost something?
No – the “new post-pandemic world” has a chance to become a safer place, as long as each of us is committed to creating a healthier social reality. So it will simply be socially responsible, which is associated with minimizing the risk of infection through appropriate behavior.
The elements of prophylaxis include frequent washing and disinfecting hands, keeping a distance, and in situations where keeping a safe distance is impossible, wearing a mask. Taking into account that testing asymptomatic people as a systemic measure is practically non-existent in our country, quick antigen tests to be performed at home allow us to ensure our own safety and that of others.
From a public health perspective, self-monitoring tests are complementary to professional antigen tests or RT-PCR performed under laboratory conditions by healthcare professionals.
* RT-PCR (reverse-transcription polymerase chain reaction).
** Test specificity is the probability of a true negative result. A truly negative result means that the person was correctly identified without infection during the examination using the specific test.
*** The sensitivity of the test is the probability of a true positive result. A truly positive result means that you were able to truly identify an infected person during the examination using the specified test.