Universitätsmedizin Berlin reported new findings on the origins of the SARS-CoV-2 variant Omicron. The team led by Prof. Jan Felix Drexler has now retracted the article, which was published in the journal Science.

Based on new findings, some of the statements made in the study can no longer be proven beyond a reasonable doubt. By retracting the article, the researchers are adhering to good scientific practice, to which Charité and the international team of authors are fully committed.

The article entitled "Gradual emergence followed by exponential spread of the SARS-CoV-2 Omicron variant in Africa" found that the Omicron variant of SARS-CoV-2 emerged in western Africa a few months before its eventual discovery in South Africa.

Shortly after the article was published, other scientists called into question the plausibility of the genome sequences analyzed in the study. In a subsequent analysis of residual samples, they were found to be contaminated. It is no longer possible to establish the source of the contamination.

One of the article's messages—that viruses with Omicron sequence signatures existed across the continent before Omicron was officially detected in South Africa—is based on collective data from PCR analysis done independently by laboratories in several African countries. However, the conclusive reconstruction of the virus's evolution, another of the article's key messages, is likely to be affected by sequence contamination not detected before analysis.

The contamination also makes it impossible to correct the analyses retrospectively in due time, because this would require additional analyses of thousands of patient samples from Africa that may not be available in sufficient quantity and quality. Therefore, in agreement with all the authors, the entire article is being retracted.

The research group that ran the project is currently carrying out an evaluation and review of the analyses. Other research groups and projects at Charité as well as those involving the consortium of authors are not affected.

Prof. Drexler and his team deeply regret the incident and are grateful to their international colleagues for flagging the potential problems following the article's publication.