“Stealth” Omicron variant does not cause alarms, but may delay the reduction of cases

recently,”Stealth “Omicron Variant” A new form of villain coronavirus Secretly creating a disastrous new wave of Covid.

That scenario is very unlikely, scientists say. However, it was called by the scientific name BA.2. Omicron virus family, Can drag the surge of Omicrons in much of the world.

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

Thomas Peacock, a virologist at Imperial College London, said:

Researchers in South Africa, November 2021 I sounded the alarm first About Omicron with 53 mutations that sets it apart from the first coronavirus strain isolated in Wuhan. Some of those mutations made it possible to escape antibodies produced by vaccines or previous infections. Other mutations seem to have concentrated it on the upper respiratory tract, Not the lungs.. Since then, genetic alterations in Omicron have made Omicron dominant around the world.

But within a few weeks of the emergence of Omicron, South African researchers began to discover. Some mysterious variants like Omicron.. The virus shared some of Omicron’s characteristic mutations, but lacked others. They also had some unique mutations of their own.

It soon became clear that Omicron was composed of three different branches separated from a common ancestor. Scientists have named the branches BA.1, BA.2, BA.3.

Early Omicron samples belonged to BA.1. BA.2 was not very common. BA.3, which was even rarer, A kind of viral sex: BA.1 and BA.2 infect the same person at the same time and their genes were scrambled together to create a new viral hybrid.

Initially, scientists focused on BA.1. This is because BA.1 occurs at a ratio of 1,000: 1 more than other BA.1. A lucky break allowed them to easily track it.

A typical PCR test usually detects three coronavirus genes. However, due to a mutation in the third gene known as spikes, the test can only identify two of these genes in BA.1.

In December, South African researchers discovered that more and more PCR tests failed to detect spiked genes. This is a sign that BA.1 is becoming more common. (The predominant variant at the time, known as Delta, did not cause spike failures in PCR tests.) As Omicron rose, Delta declined.

Unlike BA.1, BA.2 has no spike mutations that fail the PCR test. Some scientists called BA.2 a “stealth” version of Omicron because it lacks the ability to track BA.2 using PCR tests.

But BA.2 was invisible. Researchers were able to follow BA.2 by analyzing the gene sequence of the sample from the positive test. And when Delta virtually disappears, scientists can use PCR tests to see the difference between BA.1 and BA.2. The sample that caused the spike failure contained BA.1, but did not contain BA.2.

In recent weeks, BA.2 has become more common in some countries. In Denmark, BA.2 accounts for 65% of new cases. Statens Serum Institut report On thursday. However, so far, researchers have found that people infected with BA.2 are more or less likely to be hospitalized than people infected with BA.1.

On Friday, the British government released Another early analysis For BA.2, we found that variants accounted for only a few percent of cases. Still, it is growing faster than BA.1 due to its high infectivity, according to a survey across the United Kingdom.

Encouragingly, British researchers have found that the vaccine is 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 with viral sequences from recent test samples.he Estimated He added that about 8% of cases in the United States have BA.2, and that number is rising rapidly.

“I’m pretty confident that it will dominate in the United States,” said Nathan Grubeau, an epidemiologist at Yale University’s Graduate School of Public Health.

While BA.2 could lead to a new surge, Dr. Grubaugh believes that Covid cases are likely to continue to decline in the coming weeks. It is also possible that BA.2 will create small bumps along the way or simply slow down the fall. The ongoing BA.1 experiment may help scientists sharpen their predictions.