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Is "Deltacron" A Hybrid Variant? Experts Confident It's Just A Lab Error


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist


It’s thought to be highly unlikely that any recombination event between Omicron and Delta would result in a more dangerous virus. Image credit: WildMedia/

“Deltacron” may sound like a Transformers villain, but it’s likely not as worrying as some media reports have made out. Scientists have said that the supposed variant is “almost certainly” not a terrifying new hybrid of the SARS-CoV-2 virus. In fact, it’s suspected to be the result of a laboratory mix-up.

Last week, a team from the University of Cyprus told local broadcaster Sigma TV they had identified a hybrid strain of SARS-CoV-2 that contains elements of both the Delta and Omicron variants. The team said 25 cases of the unusual variant had been identified, a surprisingly high number of which were among hospitalized patients, and they had sent genetic sequences of the strain to GISAID – an international database that tracks mutations. 


They argued the strain – dubbed “Deltacron” by the media – was created by a person being co-infected with two variants at the same time. This resulted in a recombination event whereby the two variants exchanged genetic material with each other, creating a coronavirus with a Delta-like foundation and Omicron-like mutations.

Most other experts aren’t so sure, however. These kinds of recombination events are possible, but they are extremely rare and not currently considered a huge risk. Instead, many scientists believe the supposed “hybrid” variant is likely due to contamination during sequencing.

“This is almost certainly not a biological recombinant of the Delta and Omicron lineages,” commented Dr Jeffrey Barrett, Director of the COVID-19 Genomics Initiative at the Wellcome Sanger Institute.


“The apparent Omicron mutations are located precisely and exclusively in a section of the sequence encoding the spike gene (amino acids 51 to 143) affected by a technological artifact in certain sequencing procedures. We published a technical description of this issue last year,” added Dr Barrett. 


Dr Tom Peacock, a virologist at Imperial College London, echoed this stance, tweeting: “The Cypriot 'Deltacron' sequences reported by several large media outlets look to be quite clearly contamination.”

He goes on to explain: “The specific region of the sequences with Omi-like mutations is also known problem area for sequencing Delta (Artic V3 amplicon 72) – it tends to drop out so any very low-level contam [sic] gets preferentially amplified and you end up with hybrid genomes.”

If the COVID-19 pandemic has taught us anything, it’s to expect the unexpected when it comes to novel viruses. That said, scientists currently think an Omicron and Delta hybrid variant isn’t too much of a concern. While there are high levels of the variants in circulation in many countries at the moment, it’s thought to be highly unlikely that any recombination event between Omicron and Delta would result in a more dangerous virus.


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