US Medicines Agency: Omikron’s rapid tests are arguably less accurate

As of: 12/29/2021 6:44 a.m.

Research by the US Food and Drug Administration suggests that the antigen tests are less sensitive to Omicron. That could lead to false negative results. The FDA still recommends the rapid tests.

According to the US health authorities, antigen tests probably do not detect a corona infection with the Omicron variant as well as previous variants. “Initial data indicate that antigen tests recognize the Omicron variant, but may have a lower sensitivity,” said the US Food and Drug Administration (FDA). Sensitivity is a measure of how likely it is that a test will show a positive result if an infection is present.

The new data are based on initial research with live viruses from real patients. The FDA had previously examined the tests with killed viruses and could not find any differences between different corona variants. According to the FDA, the new data better reflect reality – but the studies have not yet been completed.

Antigen testing is still recommended

The FDA went on to state that the use of antigen testing is still recommended – but people should follow official directions. In some of the so-called quick tests, for example, the user is instructed to perform two tests spaced apart by a certain period of time in order to confirm a negative finding.

If a person tested negative with a rapid test but is likely to have Covid due to symptoms or their proximity to infected people, they are still advised to take a PCR test – the “gold standard” for detecting corona infections.

PCR tests are more accurate

The difference between PCR tests and antigen tests is that the latter react to protein fragments (proteins) from the envelope of the virus. However, this is mutated in numerous places in the Omikron variant. PCR tests, on the other hand, prove the genetic material of the virus. They are more accurate because they can make millions of copies of the virus’s RNA so that even the smallest amounts can be detected.

The advantage of antigen tests, however, is that they can be used at home, show a result in minutes, and are inexpensive, whereas PCR tests take hours and require samples to be examined in a laboratory. In addition to vaccination, both types of test are an indispensable part of a comprehensive strategy to contain the pandemic.

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