What is a subvariant?What you should know about Omicron BA.2

key takeaways

  • A new sub-variant of COVID-19, called BA.2, has been detected in parts of Europe, Asia and the United States.
  • Researchers are still learning more about the transmissibility, effects, and symptoms of BA.2.
  • Experts believe vaccination could provide some protection against the new subvariant, although more data are needed.

According to the World Health Organization (WHO), new versions of Omicron variants are circulating in many countries around the world. The group recommends that researchers start investigating whether the latest version behaves differently than Omicron, and whether it poses a new challenge or threat to the current pandemic situation.

The new strain of the virus is called BA.2, which is a sub-variant of Omicron (also called BA.1, according to virologists). The World Health Organization reports that BA.2 differs from Omicron because of variations in some of its mutations, including those in the viral spike protein.

As of now, health experts and researchers know very little about the new sub-variant.

“It’s a bit of a mystery at this point,” Jeremy Luban, a professor of molecular medicine, biochemistry and molecular pharmacology at the University of Massachusetts Medical School, told VigorTip. “We don’t even know where BA.2 came from or where Omicron came from. Where, there’s a lot of good ideas about it, but the truth is we don’t know.”

Here’s everything we know about the new strain so far, including where it is now and whether health experts think it’s worth watching.

What do we know about BA.2 now?

BA.2 currently exists in many countries. BA.2 accounts for almost half of all cases in Omicron, Denmark, according to the Statens Serum Institut, a Danish government research institute.

“Last week in Denmark, BA.2 was about 60% of the cases, they also had BA.1, but it looks like BA.2 is replacing BA.1,” Luban said. “We’re also seeing high levels of presence in certain regions, including several countries in Asia.”

BA.2 was designated on 21 January 2022 as a variant under investigation by the UK Health Security Agency due to the increasing number of cases detected domestically and internationally. While the BA.2 is currently most prominent in Denmark, the variant is emerging in India, Sweden and Singapore, Luban said. This subvariant has also been reported in the United States, including Washington, Texas, New Mexico, and California.

“We’re just starting to detect it, the first sequences are just emerging. They’re few in number, but it’s here,” Luban said. “You can see the numbers go up, they’re small, but as we’ve seen with Omicron BA.1, that could change very quickly.”

While it’s unknown when and where BA.2 first appeared, it’s an offshoot of the original Omicron variant, Daniel Kuritzkes, MD, a professor at Harvard Medical School and chief of the Division of Infectious Diseases at Brigham and Women’s Hospital, told VigorTip. months ago.

“BA.1 and BA.2 were detected in a similar time frame, and both originated from the same ancestral virus,” Kuritzkes said. “Why BA.2 is now becoming more frequent than BA.1 in some countries, it’s hard to predict if it will take off like the original Omicron.”

Why is BA.2 considered a subvariant?

BA.2 is a descendant of the original Omicron variant. Because BA.2 shares a common lineage with BA.1, it is currently considered a sub-variant, Luban said.

Other experts support this, including Sri Banerjee, MD, PhD, a faculty member in Walden’s public health program, who told VigorTip in an email that it’s about the similarities in the genetic makeup of BA.1 and BA.2.

“BA.2 shares 32 mutations with BA.1, making BA.2 a sub-variant rather than a novel variant,” Banerjee said. “BA.2 is widely considered to be more cryptic than the original version of Omicron because specific genetic features make it harder to detect.”

However, if BA.2 continues to spread and infect people in large numbers, it could be designated as a unique variant to differentiate it from Omicron.

“BA.1 and BA.2 are lumped together in this Omicron category, but I believe if BA.2 takes off the way it looks now, it might get its own name,” Luban said. “We might have a new Greek letter.”

How is BA.2 different from the original Omicron variant?

According to the World Health Organization, while Omicron and BA.2 are considered closer than other viruses such as Alpha, Delta, and Gamma, they still differ in important ways. There are differences in some mutations, including the spike protein, which affects how easily strains can be distinguished.

Kuritzkes said BA.2 shares many, but not all, mutations found in Omicron. While the new subvariant has unique mutations compared to the original, how efficiently it enters cells, or how it neutralizes antibodies and vaccines, is still being explored.

“BA.2 has many mutations that BA.1 does not have, and those mutations are located in regions of the genome that we care about,” Luban said. “It’s like when Omicron first appeared. In the first few days, we had a sequence, and the sequence itself was scary, but it will take time for us to find out if Omicron is more pathogenic and contagious.”

what does this mean to you

The researchers are still learning more about the new subvariant BA.2. People should continue to follow health guidance, such as social distancing, wearing masks, and getting vaccinated to prevent serious illness against COVID-19 and any potential new strains.

How spread is it?

According to recent data from Denmark, the subvariant spread rapidly. Health officials say more information is needed at this time before determining the contagiousness of BA.2.

“BA.2 was 1.5 times more contagious than the original Omicron, but did not appear to lead to an increase in hospitalizations in Denmark,” Banerjee said. “However, as we still have too little information at the moment, higher transmission rates are being monitored.”

It’s unclear if the new version spreads faster than BA.1 or if it causes more severe symptoms.

“It will take time to answer how contagious it is compared to existing viruses, the severity of the disease, and the cross-protection we see from vaccines,” Kuritzkes said. “You need to accumulate cases to see how fast this variant is spreading, and we don’t have that right now.”

While researchers are still learning more about the new sub-variant, experts don’t want people to panic. The virus is constantly mutating, mostly in harmless ways, Banerjee added. Other experts stressed that there is no evidence that BA.2 is more harmful than Omicron.

“Anytime things change, until we know more, it’s a cause for concern,” Luban said. “There’s a lot of data that if you’re vaccinated, you’re likely to be protected from serious illness or death from contracting any virus we’ve seen so far.”

While we don’t yet know whether the vaccine protects against this new subvariant, the researchers say that because the subvariant’s genetic sequence is similar to Omicron, the vaccine could provide some protection against BA.2.

“It’s clear that a vaccine protects you from severe disease against Omicron and other variants we’ve seen, so there’s no reason to think the same won’t happen with this new variant, BA.2,” Luban said.

It is currently safe to assume that vaccination may confer protection against the subvariant.

“We didn’t formally know until we saw laboratory data on how vaccine-induced antibodies neutralized BA.2,” Kuritzkes added. “But since we know the vaccine protects against severe disease in BA.1 and provides some protection against being infected, it should provide similar protection in BA.2.”

The information in this article is current as of the date listed, which means that you may have updated information as you read this article. For the latest updates on COVID-19, visit our Coronavirus news page.

Correction – January 31, 2022: A previous version of this article incorrectly referenced Sri Banerjee. It has been updated to reflect the correction of BA.2’s impact on hospitalization in Denmark.