Other scientists have speculated that Leonidos Kostrikis’s findings are a result of laboratory contamination. But he told Bloomberg in an emailed statement Sunday that 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.”

Deltacron infection is higher among patients hospitalized for COVID-19 than among non-hospitalized patients, so that rules out the contamination hypothesis, said Kostrikis, a professor of biological sciences at the University of Cyprus and head of the Laboratory of Biotechnology and Molecular Virology.

What’s more, the samples were processed in multiple sequencing procedures in more than one country. And at least one sequence from Israel deposited in a global database exhibits genetic characteristics of deltacron, he said.

“These findings refute the undocumented statements that deltacron is a result of a technical error,” Kostrikis said.

Viral genes determine the forms of proteins that perform a number of specific tasks. Omicron and delta each have mutations in the spike protein that affect their ability to enter human cells, with omicron becoming more infectious as a result.

Recombinant forms of viruses can arise when there are multiple variants of a pathogen circulating, said Nick Loman, a microbial genomics professor at England’s University of Birmingham who studies the coronavirus. While a recombinant form of delta and omicron wouldn’t be a complete surprise, the finding from Cyprus is more likely a “technical artifact” that arose in the process of sequencing the viral genome, he said. 

Cypriot Health Minister Michael Hadjipantela said Sunday that the new variant isn’t of concern, and more details will be given at a news conference this week, Philenews reported.