Covid lab technicians in India on Friday Jan. 7, 2022.
Bloomberg | Bloomberg | Getty Images

Global health experts are casting doubts over reports of a new possible Covid-19 mutation that appeared to be a combination of both the delta and omicron variants, dubbed as “deltacron,” saying it’s more likely that the “strain” is the result of a lab processing error.

At the weekend it was reported that a researcher in Cyprus had discovered the potential new variant. Bloomberg News said Saturday that Leondios Kostrikis, professor of biological sciences at the University of Cyprus, had called the strain “deltacron,” because of its omicron-like genetic signatures within the delta genomes.

Kostrikis and his team said they had found 25 cases of the mutation, with the report adding that at the time it was too early to tell whether there were more cases of the apparent new strain or what impact it could have. Bloomberg reported that the findings had been sent to Gisaid, an international database that tracks changes in the virus, on Jan. 7.

Deltacron ‘not real’

Some experts have since cast doubt over the findings, with one World Health Organization official tweeting Sunday that “deltacron,” which was trending on the social media platform on the weekend, is “not real” and “is likely due to sequencing artifact,” a variation introduced by a nonbiological process.

WHO Covid expert Dr. Krutika Kuppalli said on Twitter that, in this case, there was likely to have been a “lab contamination of Omicron fragments in a Delta specimen.”

In another tweet, she noted wryly, “Let’s not merge of names of infectious diseases and leave it to celebrity couples”

Other scientists have agreed that the findings could be the result of a lab error, with virologist Dr. Tom Peacock from Imperial College London also tweeting that “the Cypriot ‘Deltacron’ sequences reported by several large media outlets look to be quite clearly contamination.”


In another tweet, he noted that “quite a few of us have had a look at the sequences and come to the same conclusion it doesn’t look like a real recombinant,” referring to a possible rearrangement of genetic material.

Fatima Tokhmafshan, a geneticist at the Research Institute of the McGill University Health Centre in Montreal, agreed, tweeting that “this is NOT a recombinant” but “rather lab contamination b/c [because] looking at recent GISAID submission from Cyprus the clustering & mutational profile indicate NO mutation consensus.”

Read more: Omicron Covid variant likely circulating for longer — and more widely — than thought, experts say

Another high-profile scientist, Dr. Boghuma Kabisen Titanji, an infectious diseases expert at Emory University in Atlanta, advised a cautionary approach, tweeting Sunday that “On the #deltacron story, just because I have been asked about it many times in the last 24h, please interpret with caution. The information currently available is pointing to contamination of a sample as opposed to true recombination of #delta and #omicron variants.”

However, she also noted that a possible mixing of the genetic material belonging to the delta and omicron variants is a possibility as both strains continue to circulate, and is a concerning proposition.

“Recombination can occur in coronaviruses. The enzyme that replicates their genome has a tendency to slip-off the RNA strand it is copying and then rejoining where it left off. With #delta and #omicron both in circulation, dual infection with both variants increases this concern,” she tweeted.

For his part, the scientist who announced he had discovered “deltacron” has defended his findings, telling Bloomberg on Sunday that the findings are not the result of a “technical error.”


In an emailed statement, Kostrikis said the cases he has identified “indicate an evolutionary pressure to an ancestral strain to acquire these mutations and not a result of a single recombination event.”