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EXPLAINED: New Variant, Or Lab Error? What You Need To Know About 'Deltacron'

An expert in Cyprus said that the so-called "deltacron" variant has been detected in 25 patients. (Representational image)

An expert in Cyprus said that the so-called "deltacron" variant has been detected in 25 patients. (Representational image)

While a Cypriot expert has said the new variant combines traits of Omicron and Delta variants, some experts have put down its discovery to a likely lab error

A group of 25 Covid-19 patients in the tiny Mediterranean island nation of Cyprus are said to have been infected by a strain of the novel coronavirus that combines features of its Delta and Omicron variants. Amid a massive surge in cases across the world, the report has understandably triggered worries about the course the already destructive pandemic may yet take. But some experts have sought to soothe nerves by pointing out that “deltacron" — as the variant is termed — may really be nothing more than a case of a lab error involving contaminated samples. Recombination of the kind that may lead to rise of such dual variants though is not unknown for viruses. Here’s what you need to know.

What Has Been Detected In Cyprus?

A professor of biological sciences at the University of Cyprus, Leondios Kostrikis, who is also the head of its Laboratory of Biotechnology and Molecular Virology, was quoted by Bloomberg as saying that they had found a strain that displays “Omicron-like genetic signatures within the Delta genomes" upon analysis of samples from 25 patients.

“There are currently Omicron and Delta co-infections and we found this strain that is a combination of these two," Kostrikis said in an interview with a TV channel, adding that they had named the strain “deltacron". Co-infection is an instance of one person contracting two different diseases at the same time, say the seasonal flu and Covid-19. It is also possible, experts say in rare cases, for a person to be infected with two variants of the novel coronavirus.


Kostrikis said his team had found 25 cases of the purported variant with 11 of the samples taken from hospitalised patients while the remaining 14 were from those managing their infections at home. He is said to have noted that it will be premature to speculate on whether more cases linked to the variant may arise or what impact it could have on the trajectory of the pandemic, which has so far caused more than 300 million confirmed infections globally and claimed over 5.5 million lives.

“We will see in the future if this strain is more pathological or more contagious or if it will prevail" over the Delta and Omicron variants, Kostrikis said, adding that he personally was of the view that the highly contagious Omicron would outcompete deltacron.

It has to be noted that deltacron is yet to be designated by the World Health Organisation (WHO) or flagged by experts in other countries. Kostrikis said that his team had uploaded the sequences of the 25 deltacron to GISAID, the international database that tracks changes in the virus, on January 7. A European Union member with a population of about 1.2 million, Cyprus has so far recorded a little over 200,000 cases of Covid-19 and less than 700 deaths from the disease.

The Cypriot health minister is reported to have said that the new variant was not of immediate concern even as more details are to be announced in the coming days.

What Have Experts Said?

As reports about deltacron’s emergence went viral, several scientists and health experts rushed to shoot down the speculation about the rise of another variant, saying that its discovery was more likely a result of lab contamination.

Imperial College London virologist Tom Peacock said in a series of posts on Twitter that “The Cypriot ‘Deltacron’ sequences reported by several large media outlets look to be quite clearly contamination", noting that it does not demonstrate key aspects that would point to the appearance of a new variant.

Another infectious diseases specialist and a member of WHO’s Covid-19 Technical Team, Dr Krutika Kuppalli was emphatic in her rejection of deltacron, saying, it “is not real and is likely due to sequencing artifact (lab contamination of #Omicron sequence fragments in a #Delta specimen)". As the world contends with new coinages that suggest the rise of mutations and transformations of the virus, she urged that “let’s not merge of names of infectious diseases and leave it to celebrity couples".

A similar tone was struck by Dr Eric Topol, the founder of the Scripps Research Translational Institute in the US, who tweeted that deltacron “‘deltacron’ is a scariant" and that it “isn’t even a real variant but scares a lot of people, unnecessarily".

Another expert, Dr Boghuma Kabisen Titanji, too, urged caution in jumping to conclusions about the rise of a new variant, saying on Twitter that one should “interpret with caution" the reports from Cyprus as “the information currently available is pointing to contamination of a sample as opposed to true recombination of #delta and #omicron variants".

Although terms like “delmicron" and “flurona" or “florona" have done the rounds amid the rise of the Omicron variant, experts have been at pains to dispel rumour mongering around the pandemic. “Delmicron" was used to suggest a surge fuelled by the Delta and Omicron variants while “florona" referred to the discovery of flu and Covid-19 in a single patient, a situation that experts have anticipated.

But Dr Kostrikis, who announced deltacron to the world, countered the experts who have dismissed it as a result of lab contamination by saying that “findings refute the undocumented statements that deltacron is a result of a technical error". Reports say he told Bloomberg in an emailed statement 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".

He pointed to deltacron’s discovery in hospitalised patients as evidence that can serve to rule out the contamination theory. He also said that at least one sequence from Israel submitted to a global database shows genetic characteristics of deltacron.

But What Is Recombination?

While more information may be necessary before confirming the finding of deltacron, it is common for a new virus variant to be formed that merges the genetic code of two separate strains or viruses. Such a phenomenon, known as ‘recombination’ has been described as “an evolutionary superpower" for a virus like Sars-CoV-2, which “allows two closely related viruses to mix-and-match their genomes into novel combinations".

This is a more supercharged change than what a virus can take on through individual mutations since the latter occurs slowly, in a piecemeal manner. “Unlike regular mutation, which proceeds slowly one change at a time, recombination can produce wholesale changes in a coronavirus genome in one single swoop," says a report in the New Scientist.

Referring to the discovery of separate variants identified in the UK and in California that “appear to have combined into a heavily mutated hybrid" in February 2021, the report noted that

coinfection with two different variants of the novel coronavirus was a route via which recombinations could occur. “If individual host cells end up harbouring the two variants, the scene is set for recombination," it said, noting though that “the recombination event may have occurred within the sample after it was taken from the infected person, not while it was inside their body", which would mean that it owed its discovery to “an accidental laboratory artefact, not a wild virus".

Scientists have since the start of the pandemic kept a eye on the emergence of any recombinants given that it may lead to the virus behaving in entirely unexpected ways with suggestions that Sars-CoV-2 itself may have been a result of a recombination of separate viruses in a bat host before it jumped to humans.

But experts have expressed doubt over the recombination hypothesis vis-a-vis deltacron. Peacock of Imperial College put a question mark on a recombination of Omicron and Delta at this stage, saying that recombinants don’t generally appear until weeks or months of two strains circulating around each other although he noted that recombinants will be found eventually.

He also said that “much of what we understand about what makes Delta more transmissible/infectious, Omicron already possess — it’s currently unclear to me what Omicron could have to gain from Delta (with what we currently know at least)".

Titanji said that “with transmission levels of #SARSCoV2 at all time highs globally, it is likely that recombination is occurring and may rise to levels that we start picking up these events more frequently. Will this lead to more concerning variants? That is possible but nobody knows".

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first published:January 10, 2022, 12:45 IST