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Omicron variant ‘stealth’ No cause for alarm, but can slow down the case of decline

In recent days, headlines about a “stealth variant ‘Omicron’ evoked the notion that a villainous new form of coronavirus was secretly creating a disastrous new wave of Covid.

Scientists say that scenario is highly unlikely. But the new variant, scientifically known as BA.2 and one of three branches of the Omicron virus family, could lead to an increase in Omicrons in many parts of the world.

So far, BA.2 does not appear to cause more severe disease, and the vaccine is just as effective against it as it is against other forms of Omicron. But it shows signs of spreading more easily.

Thomas Peacock, a virologist at Imperial College London, said: “This could mean higher infection levels in places that haven’t peaked, and a downward trend in places where Omicrons already peak, for know.

In November 2021, researchers in South Africa First time raising alarm about Omicron, carrying 53 mutations that make it different from the original coronavirus isolated in Wuhan. Some mutations allow it to escape antibodies produced by vaccines or previous infections. Other mutations seem to have made it concentrated in the upper respiratory tract, not in the lungs. Since then, Omicron’s genetic changes have made it a worldwide domination.

However, within weeks of Omicron’s appearance, researchers in South Africa began to find some confusing Omicron-like variants. These viruses share some Omicron-specific mutations, but lack others. They also carry some of their own unique mutations.

It is clear that the Omicron is made up of three distinct clades that branched off from a common ancestor. Scientists named the branches BA.1, BA.2 and BA.3.

The earliest Omicron samples belong to BA.1. BA.2 is less common. BA.3, even rarer, seems to be the product of a kind of contagious sex: BA.1 and BA.2 infect the same person simultaneously, and their genes are shuffled together to create a new hybrid virus.

At first, scientists focused their attention on BA.1 because of its occurrence more than others with a ratio of 1,000 to one. A lucky break made it easy for them to track it down.

Conventional PCR tests typically detect three coronavirus genes. But the tests can only identify two of those genes in BA.1 because of a mutation in a third gene, called a mutation.

In December, researchers in South Africa found that an increasing number of PCR tests were failing to detect the mutated gene – a sign that BA.1 is becoming more common. (The dominant variant at the time, known as Delta, did not cause mutation failure in PCR tests.) As Omicron increased, Delta weakened.

Unlike BA.1, BA.2 lacks a spike spike that causes PCR tests to fail. Inability to use PCR tests to track BA.2, some scientists have nicknamed it the “stealth” version of Omicron.

But BA.2 isn’t invisible: Researchers can still track it down by analyzing the genetic sequence of samples from positive tests. And once Delta is almost gone, scientists can use PCR tests to tell the difference between BA.1 and BA.2: Samples that cause mutation errors contain BA.1, while the samples did not contain BA.2.

In recent weeks, BA.2 has become more popular in some countries. In Denmark, BA.2 accounts for 65% of new cases, the Serum Institute claims report on Thursday. So far, however, researchers have found that people infected with BA.2 are no more likely to be hospitalized than people with BA.1.

On Friday, the British government released another initial analysis of BA.2, found that the variant accounted for only a few percent of the cases there. However, surveys across the UK show it is growing faster than BA.1 because it is easier to transmit.

Undoubtedly, British researchers have found that the vaccine is just as effective against BA.2 as BA.1.

Trevor Bedford, a virologist at the Fred Hutchinson Cancer Center in Seattle, found a similar pattern in the United States in viral sequences from recent samples. He estimates that about 8% of cases in the United States are BA.2, and that number is growing rapidly, he added.

“I’m pretty sure it’s going to become dominant in the US,” said Nathan Grubaugh, an epidemiologist at the Yale School of Public Health.

It is conceivable that BA.2 could lead to a new wave of spikes, but Dr. Grubaugh thinks it is more likely that Covid cases will continue to decline in the coming weeks. It is also possible that BA.2 could create a small bump on the way down or simply slow down the descent. Experiments on BA.1 are currently underway that may help scientists further clarify their predictions.

https://www.nytimes.com/2022/01/30/health/stealth-omicron-variant.html Omicron variant ‘stealth’ No cause for alarm, but can slow down the case of decline

Fry Electronics Team

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