What is known about the BA.2 variant

As the proliferation of Omicron coronavirus subsides, researchers are turning to a highly contagious subvariant known as BA.2. Although it does not appear to be capable of triggering a new wave of large-scale infections, this variant may slow the decline of current COVID cases and make treatment more difficult.

This is what we have known about BA.2.

It’s not really new.

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Scientists first discovered the Omicron variant in November, and it soon became clear that the viral strains already existed as three genetically distinct varieties. Each branch of Omicron had its own set of mutations. At the time, the most common was BA.1, which quickly spread around the world. BA.1 was almost the complete cause of the record surge in this winter’s incident.

Initially, BA.1 was 1000 times more common than BA.2. However, at the beginning of 2022, BA.2 began to be discovered in most of the new infections.

It seems easy to catch.

All versions of Omicron are so contagious that this variant rapidly crowded previous forms of coronavirus, such as Delta. However, many studies have shown that BA.2 is even more contagious than BA.1.

In Denmark, for example, scientists have investigated the spread of both subvariants within a household. They found that people infected with BA.2 were much more likely to be infected with people who shared a home than those infected with BA.1. In the United Kingdom, researchers have found that people with BA.2 take less time to infect another person on average, accelerating their spread throughout the community.

It hasn’t yet caused a new surge in the United States, and probably won’t.

At the beginning of 2022, BA.2 became more common in many countries. By February, it had become globally dominant and pushed down the once dominant BA.1. In the United States, the Centers for Disease Control and Prevention estimated that BA.2 jumped from 1% in early February to 11% in early March. It could soon become dominant in this country as well.

The story continues

But that doesn’t mean that Americans are riding a new BA.2 wave that is infecting many new people. As BA.2 became more common in the United States, the total number of new cases decreased by about 95%. Around the world, daily new cases have dropped by half of their peak in late January.

As many countries have relaxed protection against the spread of COVID, BA.2 may be more likely to drive the growth of new cases. A March 10 report from a British researcher suggests that it may be happening there now.

However, there are several reasons why public health researchers doubt that BA.2 will drive a major new surge.

Existing vaccines work against BA.2 variants.

One of Omicron’s most striking features was its ability to partially circumvent vaccine protection. “Breakthrough” infections have become more common and have helped boost the proliferation of cases to record highs. However, the vaccine continued to protect people, especially those with booster immunity, from serious illness. During the Omicron surge, the vaccine remained very effective for hospitalization.

UK health officials have compared the effects of vaccines on BA.1 and BA.2 infections. They found that there was little difference between the two subvariants. And in both, booster shots provide fairly strong protection against infection and very strong protection against hospitalization.

The BA.2 variant is vulnerable to antibodies produced by the immune system after the initial Omicron infection.

When Omicron first appeared, scientists were surprised at how it could effectively avoid the immunity caused by infection with previous mutants. This is because there are mutations that change the surface of the virus, making it difficult for antibodies against previous variants to attach to the virus.

Since BA.2 has many unique mutations that set it apart from BA.1, researchers wondered if immunity from BA.1 infection could be avoided. It doesn’t seem to be the case. The World Health Organization has stated that infection with BA.1 provides strong protection against infection with BA.2.

BA.2 does not seem to be more serious than previous versions of Omicron.

The Omicron variant proved to be paradoxical: it was highly contagious, but individual infections were less likely to lead to serious cases of COVID on average than infections from the Delta mutant. .. As a result, many people have mild Omicron infections. But that didn’t mean that the Omicron surge was “gentle.” Infecting more people than ever has led to an astonishing number of hospitalizations and deaths.

Studies on Omicron have revealed several reasons for its reduced severity. Vaccination and infection with previous variants has provided many with immune defenses that prevent COVID from becoming uncontrollable. Omicron has also been shown to be inherently less severe and less damaging to the lungs than other mutants.

A similar experiment is underway in BA.2. Japanese researchers who infected two variants of hamsters found that BA.2 causes a more serious illness. However, it is not clear how good model hamsters are for humans. British researchers have found that BA.2 infection has a lower risk of hospitalization than BA.1.

Some licensed medicines work against BA.2. Others don’t.

Like BA.1, BA.2 can avoid most monoclonal antibody therapies approved by the Food and Drug Administration and disable them. Some treatments, such as AstraZeneca’s Evusheld, will continue to work. The antiviral drugs Paxlovid, Molnupiravir, and Remdesivir are all very effective against both Omicron variants when taken immediately after a positive test.

The BA.2 “Stealth Variant” nickname is outdated.

BA.2 is called a “stealth variant” because BA.2 did not reveal its presence in a positive PCR test sample, and researchers can distinguish Omicron cases from Delta and other mutant cases. It was difficult for me. BA.2 had a mutation that concealed one of the three overt coronavirus genes detected in the test.

Missing mutations are not a problem, as the majority of positive tests are related to Omicron. Almost all viruses detected by PCR are BA.1 and those that are not are BA.2.

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