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Meet ‘Deltacron,’ the Delta-Omicron hybrid COVID variant acknowledged by the World Health Organization this week

March 12, 2022, 2:27 AM UTC

Deltacron—is it, or isn’t it?

That’s been the question since Jan. 7, when a virologist at the University of Cyprus announced that he had identified several SARS-CoV-2 genomes with features of both Delta and Omicron variants of COVID—recombinants, as they’re called.

That man, Dr. Leondios Kostrikis, and his team uploaded 25 of the sequences to GISAID, an international research organization that tracks changes in COVID and the flu virus, that day, and 27 more a few days later, according to a Jan. 21 Nature piece titled “Deltacron: the story of the variant that wasn’t.”

The next day, Bloomberg picked up the news.

Overnight, the so-called Deltacron became an international story.

Not so fast, some experts cautioned, with many insisting that a recombinant hadn’t been born, but that the sequences discovered were the likely product of laboratory contamination.

As it turns out, the naysayers were wrong. World Health Organization COVID-19 technical lead Dr. Maria Van Kerkhove, an infectious disease epidemiologist, addressed the variant at a Wednesday media briefing, acknowledging the existence of the blend of Delta, also known as AY.4, and Omicron, also known as BA.1.

It’s been identified in France, the Netherlands, and Denmark, she said, adding that so far, levels of detection are “very low” and that such mutations come as no surprise.

“This is something that is to be expected, given the large amount of circulation, the intense amount of circulation we saw with both Omicron and Delta,” she said.

“This is what viruses do. They change over time.”

Additionally, COVID is infecting animals, with possibility of infecting humans again, creating additional chances for mutations.

“So, again, this pandemic is far from over,” she said. “We cannot allow this virus to spread at such an intense level.”

The development of recombinants is common among viruses, said Dr. Phoebe Lostroh, a Harvard-trained microbiology professor at Colorado College, a private liberal arts college in Colorado Springs.

Microbes—which include bacteria, viruses, fungi, and protozoa—”evolve faster than we do because they can reproduce in such a short time,” she said.

Case in point: the flu.

“The interesting thing is that every global (flu) pandemic since 1918 has had at least some genes from the flu pandemic of 1918-1919, all these years later,” she said.

While the presence of Deltacron doesn’t necessarily concern her—so much is currently unknown, including severity and transmissibility—Lostroh is concerned about the continuing evolution of COVID.

“It could outpace the human desire to implement safety measures,” she said. “We tend of think of these as restrictions. We would do well to consider them as safety measures instead.”

Lostroh encourages people to follow the guidance of their local public health agency, consulting such agency’s advice as they would a weather forecast.

“If it’s going to rain, carry an umbrella. If it’s going to be a bad COVID day, wear a mask.”

But, as with all things, the advice of public health entities are subject to the influence of politics, Lostroh points out.

“Even the CDC is now making recommendations based on politics instead of what’s best for public health,” she said. “In a case like this, with a circulating respiratory virus, collective action is really important.

“It’s hard to convince the American public that’s the case.”

What we know so far:

  • Changes in Deltacron’s epidemiology—including how fast it spreads and how severe it is—have not yet been witnessed, Van Kerhove said Wednesday, adding that multiple studies are underway.
  • Deltacron has been found in the U.S., USA Today reported Thursday, citing a report, soon to be published on research website MedRxiv, it obtained a copy of. MedRxiv publishes preprints of work that haven’t undergone peer review.
  • It appears that Deltacron isn’t just one entity. The yet-unpublished report cites 22 instances of infections involving a combination of Delta and Omicron components, including one case that had components of Delta, Omicron, and Deltacron, USA Today reported.
  • So far scientists have not assigned a name to the so-called Deltacron, a veritable media portmanteau.

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