Omicron Subvariant BA.2: What You Need To Know

As the Omicron subvariant spreads in the United States, an infectious diseases specialist shares what experts know so far about the highly contagious variant and how to protect yourself and others.

illustration of coronavirus representing omicron subvariant ba.2

The highly contagious subvariant of Omicron known as BA.2 has taken hold as the most prevalent COVID-19 variant in the world, accounting for 86% of cases reported between February 16 and March 17, according to the World Health Organization. In the United States, the subvariant is also gaining ground, with the Centers for Disease Control and Prevention (CDC) estimating that BA.2 is responsible for more than half of new COVID-19 infections in the country. The variant is most prevalent in the Northeast, accounting for 84% of cases in the New York area.

Dr. Yoko Furuya, expert on Omicron subvariant BA.2

Dr. Yoko Furuya

“Based on the rate of increase, the CDC expects BA.2 to become the dominant strain in the U.S. in the upcoming weeks,” says Dr. Yoko Furuya, Chief Epidemiologist and Medical Director of Infection Prevention and Control for NewYork-Presbyterian Hospital. “At the moment, however, BA.2 is not yet causing a new big COVID-19 surge in the U.S. like what is being seen in other countries, although experts are keeping a close watch to see if we might start entering another COVID-19 wave.”

Omicron BA.1 was responsible for the huge spike in cases that the United States experienced in the winter. But as COVID-19 cases have declined — and mask mandates and restrictions continue to ease — Dr. Furuya explains what people should know about the Omicron subvariant BA.2, including the most effective treatments, whether people can become reinfected, and how to continue to protect ourselves in this current phase of the pandemic.

Health Matters: How is BA.2 related to Omicron?
Dr. Furuya: Omicron is really a variant “family” of the virus that causes COVID-19, with multiple offshoots, or subvariants. These subvariants are closely related to each other, but they also have genetic mutations that make them behave a little differently from one another. BA.2 is one of these subvariants in the Omicron virus family, and it is now causing surges in COVID-19 infections in numerous countries in Europe and Asia. It seems to be even more transmissible than the BA.1 subvariant that was responsible for the recent U.S. Omicron wave.

How much more transmissible is BA.2?
Estimates vary, but studies show that BA.2 is anywhere between 30% and 60% more transmissible than BA.1.

Are patients getting sicker from BA.2? What are the symptoms?
While a laboratory study initially suggested that the BA.2 virus could potentially make infected people sicker than BA.1 (showing that it replicated more quickly than BA.1 in respiratory tract cells), so far the data in humans does not suggest that people are getting sicker from BA.2 than they do from BA.1. Patients with the BA.2 subvariant present with symptoms that are similar to BA.1, such as cough, congestion or runny nose, and headache, as well as some dizziness and fatigue.

What are effective treatments for the subvariant?
Paxlovid, the antiviral oral pill produced by Pfizer, appears to be effective against BA.2, as do other antivirals like molnupiravir and the intravenous antiviral drug remdesivir.

In terms of monoclonal antibody treatments, some appear to be more effective than others. The most effective are bebtelovimab, a monoclonal antibody used for treatment for mild infection in higher-risk people, as well as Evusheld (tixagevimab and cilgavimab), which is used as prophylaxis to protect against infection in moderately or severely immunocompromised people.


“At the moment, BA.2 is not yet causing a new big COVID-19 surge in the U.S., although experts are keeping a close watch to see if we might start entering another COVID-19 wave.”

— Dr. Yoko Furuya

Are the vaccines protective against the Omicron subvariant BA.2?
Yes, all of the FDA-authorized COVID-19 vaccines appear to protect against BA.2. Overall, the CDC continues to generally recommend mRNA vaccines such as Pfizer or Moderna over the Janssen (Johnson & Johnson) vaccine to protect against any COVID-19 strain including BA.2.

Are people who were infected with BA.1 protected from BA.2?
Generally, people who were recently infected with BA.1 are protected from being reinfected with BA.2, although rare reinfections have been reported. We also know that the more time passes after a previous COVID-19 infection, the more your immunity wanes, so your risk of being reinfected especially with a different strain starts increasing after several months.

Is the surge in cases in Europe and Asia any indication of what we can expect in the U.S.?
It’s not clear yet whether the COVID-19 trends in the U.S. will mirror what’s being seen in many parts of Europe and Asia. One reason things could look different in the U.S. is that we had an enormous BA.1 Omicron wave very recently, so people who were infected with BA.1 are unlikely to get infected with BA.2 in the next few months. It’s possible that could protect us to some degree from another big wave imminently, but it’s too soon to say.

With mask mandates lifting, what should people keep in mind in terms of precautions and how to best protect themselves?
Knowing that COVID-19 isn’t going away anytime soon, we’re now all trying to figure out how best to live with the virus and how to adjust what we do based on future waves and variants that we are likely to see. First and foremost, the best way to protect yourself is to get vaccinated and to get a booster if you are eligible. Even with the most recent Omicron BA.1 wave, fully vaccinated people were much less likely to get infected than unvaccinated people, and they were also extremely unlikely to be hospitalized from COVID-19. This protection was even greater for people who had received the COVID-19 booster.

While the CDC and many states have relaxed masking requirements for areas with low community transmission of COVID-19, it’s important for people to be prepared to go back to masking and taking other precautions when the numbers go back up again. If numbers in your community go into the CDC high-risk level, it is recommended that you resume masking indoors. I would also consider avoiding large crowded places as well as indoor spaces where masking is not feasible, such as indoor dining in restaurants and bars.

For some people, like those who are elderly or those with weakened immune systems, it may be prudent to keep taking precautions like masking indoors even if community transmission rates are low, but particularly when they start to go into the CDC medium-risk level. The same precautions might be considered if you live in the same household as someone who is elderly or has a weakened immune system, or people who encounter these types of individuals at work, such as healthcare workers.

Another consideration for everyone is to take extra precautions during the weeks leading up to a large social gathering, like a family get-together, or before a planned trip. Being vigilant about masking and avoiding potential exposures could prevent your plans from being interrupted or, even worse, leading to transmission to your friends and family.

Finally, even when community transmission is low, everyone should continue to take seriously any potential symptoms of COVID-19 (such as fever, cough, sore throat, head and body aches, etc.), self-isolate, and get yourself tested. Testing before large get-togethers may also be a good idea, especially if vulnerable people (elderly or immune compromised) are attending.

Yoko Furuya, M.D., is a nationally recognized epidemiologist and specialist in infectious diseases, with 20 years of clinical experience. She is the Medical Director of Infection Prevention & Control and Director of Antibiotic Stewardship for all campuses of NewYork-Presbyterian Hospital, including NewYork-Presbyterian/Columbia University Irving Medical Center and NewYork-Presbyterian/Weill Cornell Medical Center. She is also Associate Professor of Medicine at Columbia University Vagelos College of Physicians and Surgeons. In 2018, Dr. Furuya was honored for her achievements in the field of healthcare epidemiology by being recognized as a Fellow of the Society for Healthcare Epidemiology of America (SHEA).