What to know about the ultra-infectious Omicron subvariants circulating the US as COVID rates rise, Broadway shows pause, and a mask mandate returns

• New, more infectious versions of COVID-19 are spreading in areas of the US.
• The new subvariants are leading to a surge in cases along parts of the East Coast.

The mayor of New York. The speaker of the House. Sarah Jessica Parker. They are just three of the many Americans who've recently caught COVID-19, in a wave of infections that's being blamed for cancelled Broadway shows, and a prolonging of the federal mask mandate for travel.

It's almost certainly all because of viral evolution within Omicron.

Coronavirus cases are on a steady uptick along the Eastern Seaboard of the US, from Washington DC to New York and Boston. The uptick is so pronounced that Philadelphia recently reinstituted its mask mandate for public indoor spaces.

The current case rates pale in comparison to those recorded in the initial Omicron surge at the beginning of the year, but wastewater data — a reliable way to track COVID — suggests the level of virus circulating in the community is going back up to heights not seen since early February in many places on the East Coast.

This uptick in the northeast is likely being driven by more infectious Omicron subvariants, which have evolved further from the Omicron that was first detected in the US in late 2021.

Though it might sound scary, this pace of reconfiguration and proliferation in the Omicron family, it's actually nothing unusual — viruses do this kind of mingling and reproducing all the time.

In fact, it's possible that this could be a sign the virus is settling into a more predictable trajectory, and some experts say that could be good news.

The Omicron subvariants to know about, from BA.2 to XE

Around the world, countries including Botswana, Belgium, and Denmark have detected other, highly infectious Omicron subvariants, such as BA.3, BA.4, and BA.5.

In the UK, where case rates have been high in the past couple of months, virus trackers recently identified a recombinant version of Omicron — a mixture of BA.1 and BA.2 — called XE. It's unclear whether XE will ever spread very far, and only a handful of XE cases have been detected so far in the US.

In the US, experts say the most prevalent coronavirus strains now are all versions of BA.2, which is responsible for about 85% of cases nationwide.

Why new Omicron subvariants aren't necessarily a bad thing

Omicron is, genetically speaking, quite different from other versions of the virus we've seen during the pandemic, and its emergence was impossible to predict. But now that Omicron is dominant, experts are cautiously optimistic that evolution of the virus may stay Omicron-specific for a little while.

So far, the newly-detected Omicron subvariants are marginally more transmissible than BA.1, giving them an advantage on the viral playing field. But these subvariants don't seem to be any more dangerous to people, and aren't causing different symptoms. They're still Omicron relatives.

Epidemiologist Katelyn Jetelina said in her newsletter last week that continued viral evolution within Omicron "may be good news," for two key reasons:

1. For now, an Omicron infection likely provides some pretty good temporary immunity against other Omicrons, which means that since already more than half of the US has had the variant, we may get a nice break from high COVID-19 case counts over the next few months.
2. Continued evolution within Omicron would help us better prepare and plan. For the past two years, COVID-19 has been on an unpredictable tear, morphing from Alpha to Beta Delta and Omicron, without giving clear clues about whether it'll bear much resemblance to previous variants. If viral evolution drifts in a more predictable, flu-like pattern, it will become much easier to plan new vaccines and be ready to tackle the virus's next moves.

We know that 99.2% of the SARS-CoV-2 virus that the world is dealing with is Omicron, and both cases and deaths are coming down. Vaccines and booster shots still work extremely well against this virus when it comes to severe outcomes, as do well-fitted respirators and face masks made from medical-grade materials.

"I'm going to try my best to avoid it," Dr. Anthony Fauci told CNN's Kate Bolduan on Wednesday of Omicron. "It will be out there, and I'm going to have to make risk assessments. I'm vaccinated, I'm doubly boosted, and I'm not careless in what I do. Does that mean I'm not going to get infected? No. I think everyone has some degree of risk. The risk is not zero for anyone unless you stay in your room and don't come out."