News of a ‘super variant’ combining Delta and Omicron spread rapidly last week, but researchers say it never existed and the sequences may have resulted from contamination.

On 7 January, virologist Leondios Kostrikis announced on local television that his research group at the University of Cyprus in Nicosia had identified several SARS-CoV-2 genomes that featured elements of both the Delta and Omicron variants.

Named by them as ‘Deltacron,’ Kostrikis and his team uploaded 25 of the sequences to the popular public repository GISAID that evening, and another 27 a few days later. On 8 January, financial news outlet Bloomberg picked up the story, and Deltacron became international news.

The response from the scientific community was swift. Many specialists declared both on social media and to the press that the 52 sequences did not point to a new variant, and were not the result of recombination — the genetic sharing of information — between viruses, but instead probably resulted from contamination in the laboratory.

“There is no such thing as #Deltacron,” tweeted Krutika Kuppalli, a member of the World Health Organization’s COVID-19 technical team based at the Medical University of South Carolina in Charleston, on 9 January. “#Omicron and #Delta did NOT form a super variant.”