A peer-reviewed German study has concluded that only around 14 per cent of people who tested positive for Covid-19 by PCR in the country were genuinely infected with the virus. The paper appeared in the journal Frontiers in Epidemiology in October 2025 and has circulated steadily since.
Its authors are Michael Günther of the University of Stuttgart, Robert Rockenfeller of the University of Koblenz and Harald Walach of the Change Health Science Institute in Basel. They analysed weekly testing data from Akkreditierte Labore in der Medizin (ALM), a consortium that handled roughly 90 per cent of German PCR tests between March 2020 and January 2023 and also ran mass antibody screening until May 2021.
The team fitted the running total of positive PCR results to the share of blood samples showing IgG antibodies. The two curves aligned, according to the study, only when the PCR figures were scaled down by a factor of 0.14, which the authors read as one positive swab in seven corresponding to a real infection, and possibly as few as one in 10.
The same fit implied that a quarter of the German population already carried antibodies from natural infection by the time mass vaccination began on December 27, 2020. Extrapolated to the end of 2021, the modelled figure reached about 92 per cent, matching a value reported by the Robert Koch Institute.
The University of Koblenz said in a statement that treating a positive PCR test as proof of infection was not scientifically tenable, though that equation had underpinned far-reaching political decisions.
Other researchers dispute the inference. Antibody levels wane over months, and people with mild infections or strong T-cell responses may never develop detectable IgG, so a later negative antibody result does not establish that an earlier PCR result was false.
The antibody figures also came from people who chose to be screened rather than from a random cross-section of the population. The authors concede that repeat testing of the same individuals distorts the later part of their series, and that the underlying ALM dataset is no longer available online.
Walach’s record has drawn scrutiny. In 2021 the journal Vaccines retracted a paper he co-wrote on vaccine-related deaths and JAMA Pediatrics retracted his study on carbon dioxide levels behind children’s face masks, after which Poznan University of Medical Sciences in Poland ended his affiliation.
The paper has fed a wider German argument over pandemic-era data that intensified after the leak of internal Robert Koch Institute crisis-team minutes in 2024. A group of chemists led by Jörg Matysik of the University of Leipzig has since written to the institute seeking answers on the testing figures.
