Stealth Omicron BA.2 COVID Variant Could Be More Dangerous, Immune-Resistant Than BA.1—Study

The Omicron COVID sub-variant BA.2 may be more dangerous than BA.1 and could pose a greater risk to public health, according to new research.

BA.2 has made headlines in recent weeks and is the subject of ongoing research after overtaking the previously dominant BA.1 Omicron type in countries like Denmark and South Africa.

Research has found that BA.2 has a significant transmission advantage over BA.1, meaning it has the potential to spread faster through populations. But other key characteristics about the variant, such as whether it leads to increased hospitalization or is more resistant to vaccines, have yet to be conclusively determined.

Early data from the U.K.'s Health Security Agency (HSA) has suggested that vaccines are as effective against BA.2 as BA.1 in terms of preventing symptomatic disease, based on people who had a booster shot.

However, on Tuesday, dozens of researchers from Japan released a study in which they said they found that BA.2 may in fact be more pathogenic—capable of causing disease—and more resistant to previous immunity than BA.1. It should be noted that the study hasn't yet gone through the peer review process in which its quality and validity will be assessed.

The researchers infected hamsters with BA.1 and then obtained convalescent sera—essentially blood samples—from them after their bodies had elicited an immune response, meaning their blood contained antibodies.

They then exposed samples of BA.1 and BA.2 to these antibodies to see what would happen. The researchers found that BA.2 was 2.9 times more resistant to the hamster samples than BA.1 was.

They further tested this finding in mice by immunizing them with cells expressing the spike protein of BA.1 and once again tested their antibodies against BA.1 and BA.2. This time, they found that BA.2 was 6.4 times more resistant than BA.1.

In addition, the researchers infected hamsters with BA.2 and BA.1 and found that the BA.2 group exhibited more health disorders such as body weight loss than in those infected with BA.1. They also found that the amount of BA.2 virus was higher in the hamsters' lungs than that of BA.1.

Recognition as a Variant of Concern

The researchers say that based on their findings, BA.2 should be given its own Greek alphabet letter and be "recognized as a unique variant of concern."

There are limitations to bear in mind, however. As mentioned, the study hasn't yet been peer reviewed and so its findings must be taken with a grain of salt for now. In addition, animal and cell culture models don't always translate accurately to humans.

Jeremy Kamil, associate professor of microbiology and immunology at Louisiana State University Health Shreveport, told Newsweek that the study "looks highly credible and rigorous" and was from "an excellent research group", but noted: "I think it's always hard to translate differences in animal and cell culture models to what's going on with regards to human disease. That said, the differences do look real.

"I'd also stress that immunity to BA.1 will mitigate against, and in most cases fully protect people from, BA.2 infection in the near term."

Ian Jones, professor of virology at the University of Reading in the U.K., said that he "can't see any flaws" in the Japanese study, but noted that cell and animal models do not perfectly mimic the situation in humans.

He agreed with the conclusion that BA.2 is "deserving of variant of concern (VOC) status," but said that current monitoring is sufficient and added: "The real experiment is ongoing in the populations of the world and, evidently, disease severity is considerably less than previously."

Mark Harris, a professor at the School of Molecular and Cellular Biology at the University of Leeds in the U.K., told Newsweek the study looked "interesting," but doubted the possibility of extrapolating lab-based data to real-world human infections.

COVID test
Someone holds a positive COVID test in this photo taken in Berlin on January 22, 2022. Scientists are still studying the characteristics of the BA.2 sub-variant. Odd Andersen/AFP/Getty