Rapid antigen tests do not work reliably in children who, according to a PCR test, are infected with the coronavirus: On average, the infections are only detected in just under two out of three cases. This is shown by an evaluation by the Institute for Quality and Efficiency in Health Care (IQWiG) of 17 studies that compared rapid antigen tests with PCR tests, the gold standard in Covid diagnostics.
As the research group led by Naomi Fujita-Rohwerder reports, a total of eight different rapid tests were used in the studies. 6355 children were tested, mostly from the US and Spain. Depending on the study, between 4 and 50 percent of the children were positive according to the PCR test.
The good news: Around 99 percent of the uninfected children were recognized as such by the rapid tests. The bad: The tests only recognized an average of around 72 percent of the infected children with symptoms (the only German study came up with this value). Only 56 percent of the infected children without symptoms were discovered.
The IQWiG team writes that no test met the minimum requirements of the World Health Organization or the US Food and Drug Administration (FDA). From May 2022, antigen tests are to be checked by independent laboratories for their approval. Manufacturers are currently allowed to certify their tests themselves that they detect an existing virus. However, the data are often “overly optimistic” and do not correspond to practice, say the researchers.
However, the tests by the manufacturer are only intended for symptomatic cases. Because they usually have a higher viral load, and then the sensitivity – the proportion of infections detected – is higher. So far, however, there is no threshold value for determining whether a person is infectious or not. The risk of infection posed by the infected children in the present study is therefore not known.