Cases of Omicron variant XBB are mounting in China, forming a new wave expected to crest around 65 million cases a week by the end of June.

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Infections will likely reach 40 million per week by the end of the month, senior health adviser Zhong Nashan told attendees at a biotech conference in Guangzhou, according to Bloomberg.

The wave could swell to become the country’s second largest, experts tell Fortune. It will undoubtedly pale in comparison to the country’s first major wave late last year, during which an estimated 37 million people were infected on one day—Dec. 20—alone.

That wave—equivalent to the early days of the pandemic for the rest of the world—occurred after the country abruptly abandoned its yearslong “zero COVID” policy, effectively letting the virus “rip” through a population that had been largely sheltered from the it—and that was vastly undervaccinated.

A ‘largely invisible’ wave

XBB, the “first major highly immune-evasive” group of COVID variants, “will sweep through China,” but the wave will be “largely invisible” due to low rates of testing and reporting, Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark., and a top COVID-variant tracker, tells Fortune.

When it comes to XBB variants, “the rest of the world has seen them all.” But up until recently, “China hasn’t,” he says, adding that the country has a substantial population at high risk of severe outcomes from COVID due to age, immune status, and co-morbid conditions.

Increased circulation of XBB variants in China—and elsewhere—is likely to result in the evolution of new XBB variants, Rajnarayanan said. So far, XBB spawn have remained relatively innocuous for those not at increased risk of severe disease, according to the World Health Organization’s latest situation report, released Thursday.

‘Go back for regular check-ups’

It remains to be seen whether hospitalizations will rise in China, Rajnarayanan and fellow variant tracker Ryan Gregory—a Canadian biologist who has assigned “street names” to so-called “high flying” variants like XBB.1.5, dubbed “Kraken”—tell Fortune.

Hospitalizations can, however, be expected to rise if variants that combine the transmissibility of XBB with the lung involvement of Delta catch on, in China or elsewhere. Trackers are eyeing variants that have a mutation in the spike protein that could cause such a phenomenon. So far, such variants are only prevalent in New Zealand and the European Union, Rajnarayanan says.

The evolution of a veritable XBB-Delta combo isn’t an inevitability, though, Rajnarayanan says.

And while the virus is capable of pivoting at any point, evolving into a more lethal version of itself, it so far hasn’t–—and the chance of it doing so isn’t any greater in China that it is in the rest of the world, where the virus is also spreading unchecked, Dr. Ali Mokdad, a professor at the University of Washington’s Institute for Health Metrics and Evaluation, tells Fortune.

While caution is always warranted when it comes to COVID, people everywhere need to “go back for regular check-ups, and bring their kids in for vaccinations,” Mokdad said.

COVID precautions “saved a lot of lives,” he added. “It’s time for us to go back to normal and make sure it’s not at the expense of other preventative programs.”

This story was originally featured on Fortune.com

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