What are the differences between omicron and BA.2?
Dr. Huerta responds 4:14
(CNN) —
The BA.2 virus — a subvariant of the omicron variant of the coronavirus — is not only spreading faster than its distant cousin, it can also cause more severe disease and appears capable of thwarting some of the key weapons we have against covid-19, new research suggests.
New laboratory experiments from Japan show that BA.2 may have characteristics that make it just as capable of causing serious illness as older variants of covid-19, including delta.
And like omicron, it seems to largely escape the immunity created by vaccinations.
A booster shot restores protection, making illness after infection 74% less likely.
BA.2 is also resistant to some treatments, including sotrovimab, the monoclonal antibody currently used against omicron.
Several places lift restrictions due to covid-19: are we entering a new era of the pandemic?
The findings were published Wednesday as a preliminary study on the bioRxiv server, before peer review.
Normally, before a study is published in a medical journal, it is reviewed by independent experts.
Preprints allow research to be shared more quickly, but are published before that extra layer of review.
advertising
"From a human perspective, it could be a worse virus than BA.1 and could be better transmitted and cause worse disease," says Dr. Daniel Rhoads, section chief of microbiology at the Cleveland Clinic in Ohio.
Rhoads reviewed the study but was not involved in the research.
BA.2 is highly mutated compared to the original virus that caused covid that emerged in Wuhan, China.
It also has dozens of genetic changes that are different from the original omicron strain, making it as different from the most recent pandemic virus as the alpha, beta, gamma, and delta variants were from each other.
Kei Sato, a researcher at the University of Tokyo who conducted the study, argues that these findings prove that BA.2 should not be considered a type of omicron and should be more closely monitored.
How worried should we be about the new "stealth" version of omicron?
What an expert says
"As you may know, BA.2 is called a 'stealth omicron,'" Sato told CNN.
This is because it does not show up in PCR tests as a failure of the S gene target, as omicron does.
Therefore, laboratories have to go one step further and sequence the virus to find this variant.
"Establishing a method to detect BA.2 specifically would be the first thing" that many countries need to do, he says.
"It looks like we might be looking at a new Greek letter here," agreed Deborah Fuller, a virologist at the University of Washington School of Medicine, who reviewed the study but was not part of the research.
Mixed real-world data on severity of subvariant BA.2
BA.2 is between 30% and 50% more contagious than omicron.
It has been detected in 74 countries and 47 states in the United States.
The US Centers for Disease Control and Prevention (CDC) estimates that around 4% of Americans with covid-19 now have BA.2 infections, but many other parts of the world have more experience with this variant.
It has become dominant in at least 10 other countries: Bangladesh, Brunei, China, Denmark, Guam, India, Montenegro, Nepal, Pakistan and the Philippines, according to the World Health Organization (WHO) weekly epidemiological report.
But there is conflicting evidence about the seriousness of BA.2 in the real world.
Hospitalizations continue to decline in countries where BA.2 has taken hold, such as South Africa and the UK.
But in Denmark, where BA.2 has become the leading cause of infections, hospitalizations and deaths are on the rise, according to the WHO.
The importance of the third dose and the use of masks against the omicron variant 2:56
Resistant to monoclonal antibody treatments
The new study found that BA.2 can copy itself in cells more quickly than BA.1, the original version of omicron.
It is also more adept at making cells stick together.
This allows the virus to create groups of cells larger than BA.1, called syncytia.
That is worrying because these groups become factories to produce more copies of the virus.
Delta was also good at creating syncytia, which is thought to be one of the reasons it was so destructive to the lungs.
When the researchers infected hamsters with BA.2 and BA.1, the BA.2-infected animals became sicker and had worse lung function.
In tissue samples, the lungs of hamsters infected with BA.2 had more damage than those infected with BA.1.
OPINION |
A humble prediction of what comes after the omicron variant of coronavirus
Similar to the original omicron variant, BA.2 was able to break down antibodies in the blood of people who had been vaccinated against covid-19.
It was also resistant to antibodies from people who had been infected with covid-19 early in the pandemic, including those with the alpha and delta variants.
And BA.2 was almost completely resistant to some monoclonal antibody treatments.
But there was a bright spot: Antibodies in the blood of people who had recently had omicron also seemed to have some protection against BA.2, especially if they had also been vaccinated.
And that raises an important point, says Fuller.
Although BA.2 appears more contagious and pathogenic than omicron, it may not end up causing a more devastating wave of covid-19 infections.
"One of the caveats that we have to think about as we get new variants that may seem more dangerous is the fact that there are two sides to the story," says Fuller.
What the coronavirus taught us in 2021: variants and advances in the fight against covid-19
The virus matters, she says, but as potential hosts, so do we.
“Our immune system is also evolving.
And that is setting things back,” she said.
Right now, he says, we are in a race against the virus, and the key question is, who is in the lead?
“What we ultimately want is for the host to be ahead of the virus.
In other words, our immunity, being one step ahead of the next variant that comes out, and I don't know if we're there yet," he said.
For that reason, Fuller says, he feels now is not the time for communities to lift mask mandates.
"Before this came out, we were about 3 meters from the finish line," he said.
"Removing the masks now is not a good idea. It will only extend it. We are going to get to the finish line."
coronavirus variants