Corona rapid tests: when they come and how reliable are they

Quick tests in the fight against the second wave: 8 things you need to know

In the fight against the second corona wave, a lot of hope is placed on rapid tests. How reliable they are, when they will be used on a large scale in Switzerland and what is expected.

What types of corona tests are there?

Crown tests can be basically divided into three categories:

• PCR test
• Antigen test
• Antibody or serological tests

PCR tests Y Antigen tests detect the virus directly; antibody-Tests do this indirectly. The first two methods mentioned can detect a current infection, whereas antibody tests are mainly used to detect an infection that has already passed.

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How exactly do rapid tests work?

Rapid tests are often referred to without defining exactly what type of test it refers to. Especially the Antigen–Tests meant. But here too a distinction must be made between the three categories:

• Rapid PCR test: The DNA of the virus is detected in PCR tests. With rapid tests, samples do not have to be transported to the laboratory, which greatly shortens testing time. In rapid tests, too, a swab is taken from the mouth, nose, or throat with a cotton swab. But there are also tests that require a saliva sample. Rapid PCR tests are also called cartridge tests, as they are delivered almost directly by the laboratory. It can analyze the genetic material of the virus so quickly that the first result is available after three quarters of an hour.
• Rapid antigen test: When it comes to antigen testing, there is no distinction between slow and fast testing procedures. The test, which detects proteins in the virus rather than the virus itself, is generally very fast. It usually works on a saliva sample that, depending on the procedure, is placed in a liquid and then applied to a test strip. The result can be read after a short time. Depending on the provider, this varies between five and fifteen minutes.
• Rapid antibody test: Antibody tests also do not detect the virus itself, but rather the reaction of the immune system to it. The tests are available in laboratory and rapid versions. In rapid tests, a few drops of blood are put into a test cassette. Then a buffer solution is added. If IgM and IgG immunoglobulins, which are typical for SARS-CoV-2, are in the blood, the sample becomes discolored.

How fast are rapid tests really?

Depending on the type of test, it can be between five minutes (Antigen tests) up to one Three quarters of an hour (Rapid PCR tests) take time until the result of a test is known.

How reliable are rapid tests?

Here, too, one must distinguish between the three different test categories.

• PCR: Time describes PCR testing as the gold standard among Covid-19 testing procedures. The PCR test is reliable under laboratory conditions. But there are always sources of error. Also, rapid PCR tests are less reliable because they are not performed under laboratory conditions.
• Antigen: Antigen tests are cheap and fast, but significantly less reliable than traditional PCR tests. About half of the negative results turn out to be false (the test does not find a virus protein, even though it is present). Therefore, the tests only detect half of all people infected with Covid 19. An antigen test from Roche should offer much better values ​​and be more reliable.
• antibody: A positive antibody test result is certainly an indication that the person tested has been infected with SARS-CoV-2 and has some immunity. However, this is not certain because antibody tests can also cross-react with other similar viruses. Furthermore, science still knows very little about how long immunity against coronavirus will last. Therefore, the antibody test (regardless of whether it is a lab or rapid version) is currently hardly recommended for people.

Are rapid tests already being used in practice?

Some airlines, including the Lufthansa Group’s Austrian Airlines, are already testing the use of Antigen–Quick tests at airports.

The test, which is voluntary and free for passengers and is supposed to provide a result after 15 minutes, is not a substitute for the less rapid PCR test. Nor does it change the strict entry requirements due to the pandemic.

When does FOPH want to use large-scale rapid tests?

The Federal Office of Public Health (FOPH) is also currently evaluating the use of rapid tests in Switzerland. It is mainly about the use of Antigen–Quick tests. At a press conference on October 22, Health Minister Alain Berset promised that they would be used as soon as possible.

“We hope to take a significant step further in the coming days,” Stefan Kuster, head of the Department of Communicable Diseases, announced at the October 23 press conference. Rapid antigen tests are very welcome, but should be integrated into a testing strategy, Kuster continues.

Who are the rapid tests for?

According to Health Minister Alain Berset, it is currently unclear how and to whom the tests will be distributed. The goal is to introduce rapid tests quickly, especially for certain groups of people, according to a BAG spokesperson for the “Handelszeitung.”

The economy and tourism have high hopes for the rapid test procedures. Rudolf Minsch, Economuisse’s chief economist, even describes it as a “game changer.” “If, for example, a crown case arises after a wedding, after a work shift or in an apartment, from now on everyone just has to do a quick test. And only those who actually test positive should also be quarantined, ”Minsch is quoted in Handelszeitung.

Who produces the rapid tests?

There are several manufacturers. The pharmaceutical company Roche announced in mid-October that it intends to bring a rapid antigen test to market this year. Roche notes in a press release that antigen testing is generally very specific. However, they are not as sensitive as PCR tests that detect the virus directly.