What is known about the “invisible” version of omicrons?

Scientists and public health officials around the world are closely following the descendant of the omicron variant, which has been found in at least 40 countries, including the US.

This version of the coronavirus, which scientists call BA.2, is widely considered to be more inconspicuous than the original omicron version because certain genetic traits make it harder to detect. Some scientists fear it may also be more contagious.

But they say there’s still a lot they don’t know about it, including whether it’s better at evading vaccines or causing more serious illness.

Where did it spread?

Since mid-November, more than three dozen countries have uploaded nearly 15,000 BA.2 genetic sequences to GISAID, the global coronavirus data-sharing platform. As of Tuesday morning, 96 of these sequenced cases have been reported in the US.

“So far, we haven’t seen it start to pick up” in the US, said Dr. Wesley Long, a pathologist at the Houston Methodist School in Texas, who identified three cases of AD.2.

The mutant is much more common in Asia and Europe. In Denmark, it accounted for 45% of all COVID-19 cases in mid-January, compared with 20% two weeks earlier, according to the Statens Serum Institut, which is run by the Danish Ministry of Health.

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What is known about this version of the virus?

BA.2 has many mutations. About 20 of them in the spike protein that coats the outside of the virus are shared with the original omicron. But it also has additional genetic changes that were not in the original version.

It’s unclear how significant these mutations are, especially in a population that encountered the original omicron, said Dr. Jeremy Luban, a virologist at the University of Massachusetts School of Medicine.

For now, the original version, known as BA.1 and BA.2, is considered a subset of omicron. But world health leaders may give it its own Greek name if it is deemed a globally significant “option of concern.”

The rapid spread of the BA.2 in some places raises concerns that it could take off.

“We have some indications that it may be just as infectious, or perhaps a little more infectious than (original) omicron, as it may compete with it in some areas,” Long said. “But we don’t necessarily know why that is.”

Initial analysis by Danish scientists shows no difference in hospitalization for BA.2 compared to baseline omicron. Scientists are still studying the contagiousness of this version and how well current vaccines work against it. It’s also unclear how well the treatment would work against him.

Doctors also don’t yet know for sure if someone who already had omicron-induced COVID-19 could get BA.2 again. But they are hopeful, especially that prior infection with omicrons may reduce the severity of the disease if someone later becomes infected with BA.2.

The two versions of omicrons have enough in common that it’s possible that infection with the original mutant “will give you cross-protection against BA.2,” said Dr. Daniel Kuritzkes, an infectious disease expert at Brigham and Women’s Hospital.

Scientists will run tests to see if antibodies from infection with the original omicron are able to “neutralize BA.2 in the lab and then extrapolate from there,” he said.

How concerned are the health authorities?

The World Health Organization classifies omicron as a whole as a variant of concern, its most serious designation for a coronavirus mutant, but does not give BA.2 its own designation. However, given its rise in some countries, the agency says the BA.2 investigation “should be a priority.”

The UK Health Safety Agency, meanwhile, has identified BA.2 as “a variant under investigation,” citing the growing number of cases found in the UK and around the world. However, the original omicron version remains dominant in the UK.

Why is it harder to find?

The original version of Omicron had specific genetic features that allowed health officials to quickly distinguish it from Delta with a specific PCR test due to what is known as “S-gene target failure”.

BA.2 does not have the same genetic quirk. So, on the test, Long said, BA.2 looks like a delta.

“It’s not that the test doesn’t detect it, it’s just that it doesn’t look like an omicron,” he said. “Don’t think that ‘invisible omicron’ means we can’t detect it. All of our PCR tests can still detect it.”

What to do to protect yourself?

Doctors are advising the same precautions they always do: get vaccinated and follow public health recommendations for wearing masks, avoid crowds and stay home when you’re sick.

“Vaccines still provide good protection against severe illness, hospitalizations and death,” Long said. “Even if you’ve already had COVID-19 – you had a natural infection – the protection from the vaccine is still stronger, lasts longer, and actually … works well for people who were previously infected.”

The latest version is another reminder that the pandemic is not over yet.

“We all want it to be over,” Long said, “but until we vaccinate the world, we will be at risk of new options.”

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