RTL’s Annick Goerens interviewed Dr Thomas Dentzer, one of Luxembourg’s leading public health experts. She raised several pertinent questions, including the current deployment of rapid testing, what kind of tests are available, who is entitled to them and whether large-crowd events are likely to go ahead any time soon.
The virologist, who is also the government task force’s official for testing, explained that a large range of rapid tests already exists. They differ from each other greatly however, as a rapid test just refers to the fact that results are yielded in a short amount of time.
Some PCR tests, which are being used as part of Luxembourg’s large-scale testing and are available on prescription, can also show results within a shorter amount of time, thus functioning as rapid tests. Generally, Dr Dentzer explained, there are three different categories of tests: PCR tests, antigen tests and antibodies tests. The latter two are often referred to as rapid tests as they show results within 15 to 20 minutes. Dr Dentzer emphasised that particularly antigen tests could prove to be useful. They are carried out through a nasal or oral swab, just like a PCR test, and yield results within 15 minutes. He said they were not unlike regular pregnancy tests.
Antigen tests are also the most frequently used. Luxembourg has ordered 900,000 such tests, which have performed well in scientific studies. However, these tests can only be carried out by healthcare professionals, which bears advantages and disadvantages according to the virologist.
PCR tests require several crucial resources, including a laboratory, chemicals, the appropriate machinery and personnel. Antigen tests, however, yield results within 15 to 20 minutes and are shown on a stick, just like a pregnancy test. The downside is though that they are less accurate and cannot detect minuscule traces of the virus, which PCR tests are able to pick up. According to Dr Dentzer, PCR tests remain the “gold standard” in testing as they are more precise and more reliable than antigen tests.
The government looked into using antigen tests as part of the large-scale testing, but for the time being it has decided against it.
Although antigen tests perform well with people who are sick and are showing symptoms, the main concern is that they are less reliable with people who do not show any symptoms, says Dr Dentzer. It frequently occurs that tests come back negative, but the person is, in fact, carrying the virus. This is why the government decided against using them on a large scale. If used in the thousands, there will still be several people whose antigen tests are negative but are infected.
Due to their limited reliability, antigen tests are only scarcely used. Still, there have been demands to deploy them in care and retirement homes, so visitors could get tested prior to entering those facilities.
The health expert says that antigen tests bear somewhat of a risk. In care homes that risk could be too high as this is a particularly volatile environment, which has seen a terrible amount of cases and fatalities. On the other hand, that risk is smaller if antigen tests are used by younger people.
Presently, researchers are also working on saliva tests, which can yield results within minutes. However, these are still in short supply, says Dr Dentzer.
