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COVID Antigen Tests: What Can They Do? How do they work

The aviation industry would like to have the new and cheap corona tests carried out quickly on a wide scale.

In the past few weeks, there have been repeated reports of rapid corona antigen tests: Simple tests are intended to make it easier, for example, to get OK for air travel or border crossings. They are cheaper, easier to carry out and, above all, faster than the previously common PCR tests. But how do these tests actually work? And above all: How well can they be used in the aviation setting?

Most of the rapid tests currently being tested or produced use so-called immunossays. Components of the virus (ie “antigens”) bind to specific antibodies and lead to a visual signal if this target antigen (ie in this case SARS-CoV-2 antigen) is in the sample. As with PCR, the sample is taken from the nasopharynx and applied to a test cassette. A buffer solution then transports the antigen over the test field with the corona antibody and on to a control strip. In the event of an infection, both the test and control fields will stain. If the result is negative, only the control strip changes its color – if there is no coloration at all, the test is invalid and cannot be interpreted. The principle is essentially known from the pregnancy test.

Not all infections are detected
So far so good. However, the corona antigen test also has a few pitfalls: it does not turn out “positive” (ie noticeable) for all infections. “The test has a sensitivity of 96.52% and a specificity of 99.68%, based on 426 samples from two independent study centers in India and Brazil,” said a spokesman for the Roche Group (who recently spoke with his “SARS- CoV-2 Rapid Antigen Test “went on the market) opposite AviationNetOnline. In plain language, this means that the test did not detect around every 30th infection under study conditions – in real conditions with a low-risk group, these values ​​could also look different. But: False negative tests can also occur with the “gold standard” PCR.

PCR tests can only be carried out with great effort – and are correspondingly expensive (Photo: Roche).

This new antigen test is also not intended to be performed by laypeople. The Roche spokesman attaches great importance to the statement that his company’s product is “not approved for personal use. It is aimed at general practitioners and laboratories.” This in turn means that medical personnel are required to perform the nasopharyngeal swabs and analyzes. So if you plan such tests on a large scale before take-offs in aviation, for example – as recently requested – you cannot do so without the appropriate infrastructure. However, this is a lot less complex than, for example, the PCR tests.

Test for less than 10 euros
The advantages of the new fast antigen tests are – as mentioned – their ease of implementation, the short waiting time for the test result (around 15 to 30 minutes) and the low price. Regarding the latter, at least Roche does not provide any official information: “We do not provide any information on the costs. In pandemic situations like this, the costs should not be an obstacle to access to diagnostics. We are committed to giving as many tests as possible to people deliver what they need. We will definitely price the test responsibly, “said the spokesman. This test can be bought in medical specialist shops for individual buyers from ordinations for just under 10 euros net, a competing product from Abbott costs less than 7 euros per unit (see DocCheck Shop).

Since the demand for these antigen tests will increase sharply in the near future, Roche would like to increase the production figures significantly: “40 million tests will be available worldwide per month. The capacities will be doubled by the end of the year. where they can be used immediately and have the greatest impact on patients, “said the company spokesman. Competitor Abbott also plans to ramp up production and produce 50 million rapid antigen tests per month. It remains to be seen whether a sufficient number of tests will be available for aviation despite the ramped up manufacturing capacities.

In any case, the airlines are eagerly awaiting this new method because it could actually make traveling a lot easier – Austrian Airlines, for example, wants to offer the test “as soon as possible” and Vienna Airport would like to add it to its repertoire as a supplement to the PCR soon. It will be exciting to see whether the widespread use of these simple and cheap tests will give the ailing aviation industry some air again.

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