Omicron Wave Review: Why Rapid Tests Are Still Useful

Mith the rapidly increasing incidences of omicrons and the 2-G-Plus rule in more and more areas such as the catering industry, the rapid antigen tests have become more important than ever as a detection instrument, but at the same time their reliability is increasingly being questioned. The Paul Ehrlich Institute has confirmed the announcement made by Federal Health Minister Karl Lauterbach on Sunday evening to carry out a separate review of the officially listed rapid tests.

Joachim Müller-Jung

Editor in the features section, responsible for the “Nature and Science” section.

The background to this are the results of smaller studies, especially in the USA, according to which the rapid tests no longer reliably provided a correct result in the first few days after infection with the strongly mutated variant. Are the rapid tests unsuitable in the current omicron wave, and would this mean that more PCR tests would have to be carried out (and paid for)?

Three reasons and more why rapid testing is still useful:

1. Limited PCR capacities

Both Lauterbach’s ministry and most virologists hold fast to the usefulness of rapid tests. This is not only due to the rapid tests themselves. According to a data analysis, the utilization of the PCR capacities of almost 2.3 million tests per week is the Accredited laboratories in medicine (ALM) increased sharply with the surge in omicron infections. The positive rate of the samples sent is already more than 23 percent, which means that further bottlenecks can be expected in the next few weeks. PCR tests are the gold standard for virus detection, they very reliably identify the infected by detecting the genetic material of the virus.

The cheaper, but also much faster, rapid tests, on the other hand, determine whether someone is currently infectious by detecting fragments from the virus envelope – and only work when the amounts of viruses in the sample material are very high and the tested are very likely to be there Moment are also contagious. In the first two to three days after infection and also after the peak of the virus replication in the nasopharynx, most of these tests do not work, you get a negative result – but most infected people are not yet or no longer highly infectious.

2. Tests do capture omicrons

Already some examinations before the Omicron wave about the Charité in Berlin had shown that the validity of the various antigen tests differed significantly from one another. Antigen tests are therefore questionable for reliable diagnoses, but as an instrument of public health protection they can help, especially with rapidly rising incidences, to prevent massive amounts of infection from highly infectious people – as long as those who test positive isolate themselves. Therefore, despite concerns about sensitivity, rapid test capacities are being expanded around the world. There are now increasing concerns about the multiple mutated Omicron variant. The replication cycle of this virus is different from previous variants. Because the time window for detecting high levels of virus in the nose and throat has apparently become smaller as a result, the risk for infected and actually infectious people of receiving a wrong result has increased.

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