A hybrid Delta and Omicron strain of COVID-19 has been discovered in several European countries and the United States - and it's even caught the attention of the World Health Organization (WHO).
'Deltacron', as it's been informally dubbed, is a recombinant virus that has melded-together genetic information from both variants.
Cases are believed to be rare, but researchers are still tracking the hybrid strain to understand how COVID-19 is changing as the pandemic goes on.
What is Deltacron?
As mentioned above, Deltacron is a recombinant COVID-19 variant that contains elements of both Delta and Omicron.
"These recombinants arise when more than one variant infects and replicates in the same person, in the same cells," Professor Lawrence Young, a virologist at the University of Warwick, told the Guardian.
"Deltacron is a product of both the Delta and Omicron variants circulating in the same population."
Earlier this week, Gisaid, a global group of scientists that shares virus information, said they had found the first piece of solid evidence that this variant exists that was shared by the Pasteur Institute in France.
Gisaid says Pasteur Institute's analysis gives "definite confirmation" of Deltacron derived from the GK/AY.4 and GRA/BA.1 lineages.
Where has Deltacron been found?
Deltacron has been identified in several regions of France, Gisaid says, and has been circulating since early January 2022.
Genomes with a similar profile have also been found in Denmark and The Netherlands.
There's also been reports of Deltacron being detected in the United States, and about 30 cases have been reported in the United Kingdom.
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Deltacron was believed to be found by researchers in Cyprus in January, although this was largely panned by experts and believed to be laboratory contamination.
The Deltacron variant hasn't been found in New Zealand.
Is Deltacron cause for concern?
Experts at WHO say that recombinant variants aren't uncommon and that they should be expected.
Dr Maria Van Kerkhove, WHO's COVID-19 technical lead, said earlier this month the Deltacron variant is expected, given the large and intense amount of circulation seen with Omicron and Delta.
"Given the sheer number of changes and mutations within Omicron, it was much easier for researchers, scientists, public health professionals, people who are studying the genome to be able to detect these recombinants," she says.
"We do expect to see the recombinants because this is what viruses do, they change over time. This is something that's on our radar, it's something we are monitoring."
This was echoed by Dr Soumya Swaminathan, WHO's chief scientist, who says that recombinants are expected given how widespread COVID-19 is.
"Testing, surveillance (including ILI & SARI), sequencing and data sharing is still important to keep track of the pandemic and take early action when new variants emerge," she tweeted.
