“Everyone is kind of tired and has given up” on COVID. But this new variant is “one to watch,” says the WHO – Fortune

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The World Health Organization has turned its eye to a new variant of COVID that is believed to be leading to a new wave of cases in India – at a time when reported cases are declining in much of the rest of the world.

XBB.1.16, dubbed “Arcturus” by variant trackers, is very similar to the US-dominant “Kraken” XBB.1.5 — the best-transmissible COVID variant to date, said Maria Van Kerkhove, technical lead for COVID-19 at the WHO earlier this week under a press conference.

But additional mutations in the virus’s spike protein, which attaches to and infects human cells, have the potential to make the variant more contagious and even cause more serious illness. For this reason, and due to increasing cases in the east, XBB.1.16 is considered “one to watch,” says Van Kerkhove.

It’s a warning we’ve heard before about other Omicron spawns – XBB.1.5 in particular. The variant, which rose to prominence late last year and early this year, sparked warnings that it could cause more serious diseases due to new mutations it had evolved.

It was a fate that didn’t work out – although the variant certainly took the lead in terms of portability. According to the WHO in early March, XBB.1.5 accounted for almost half of all cases sequenced worldwide.

Only time will tell if and what differences in severity XB.1.16 will exhibit. Mutations that appear to be of concern in theory are not always of concern in real life due to the highly complex nature of population immunity.

Regardless, “the rapid increase in Arcturus in India is worrying,” Ryan Gregory, a biology professor at the University of Guelph in Ontario, Canada, tells Fortune. He led the development of “street names” for COVID variants when it became clear the WHO would not assign new Greek letters to them.

That XBB.1.16 appears to be gaining momentum in a country with strong population immunity to both past infection and immunity is worrying, notes Gregory. While it’s not clear how big the surge in the new variant might be in India or elsewhere, “big waves are no longer the main pattern” of COVID cases, he says. “It’s the consistently high baseline that won’t go down.”

Here’s what we know so far about the latest twist to raise eyebrows — and the first to do so in several months.

When and where was XBB.1.16 discovered?

XBB.1.16 was only recently added to the WHO’s list of monitored variants on March 22. COVID surveillance is at an all-time low. So far, however, the majority of cases have been identified where the new variant was first detected, in India – one of the few countries where the number of registered COVID cases is increasing, according to the WHO.

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Where else has XBB.1.16 been seen?

From reported sequences we know that the variant has also been discovered in the US – California, New Jersey, Virginia, Texas, Washington, New York, Illinois, Minnesota, Georgia, Florida, Pennsylvania, Ohio, Nevada, Indiana, North Carolina, Louisiana and Delaware to be exact.

A progeny variant, XBB.1.16.1, has also been seen in Nebraska, Missouri and Michigan.

None of the new variants accounted for enough sequences (1% nationwide) to be included in the updated COVID forecast from the US Centers for Disease Control and Prevention on Friday. Sequences from both are still grouped under XBB, which accounts for an estimated 2.5% of current cases in the country.

XBB.1.16 and its descendants have also been identified in Singapore, Australia, United Kingdom, Japan, Israel, Canada, Malaysia, Denmark, New Zealand, Germany, South Korea, Spain, the Netherlands, Thailand, Sweden, South Africa, Italy, and China.

How did XBB.1.16 develop?

The variant is a recombinant or combination of two offspring of the so-called “Stealth Omicron” BA.2. Compared to the “grandparent” line XBB, it has three additional mutations according to the WHO.

And it’s picking up additional mutations, Raj Rajnarayanan, associate dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark., and a top tracker of COVID variants, tells Fortune.

Will XBB.1.16 cause an increase in hospital admissions and deaths?

No laboratory studies on the severity of the variant’s disease have been completed to date. According to a WHO COVID-19 situation report on Thursday, hospitalizations, intensive care unit admissions and deaths due to the variant have not yet risen.

Although the variant does not cause “large clusters” of diseases, it does lead to a “steady rise in new cases” across India, Ma Subramanian, health minister of India’s Tamil Nadu state, said on Friday, The Times of India reported.

So why is XBB.1.16 so worrying?

Whether the new variant can actually lead to an increase in hospital admissions or deaths may be too early to say. Uptrends in such metrics can take weeks to become apparent, which is why they were known as “lagging indicators” at the start of the pandemic.

XBB.1.16 notably has two new mutations that “make it fitter than any previous variant,” says Rajnarayanan. These two mutations do not exist on the relative XBB.1.5.

“Right now, XBB.1.16 is the big dog,” he says. “It picks up mutations common in other variants that will further increase its advantage.”

Of particular concern is the K478R mutation, which the WHO says may make the variant better at overcoming antibodies from previous infections and vaccinations, making people sicker and spreading more widely.

Additionally, XBB.1.16 has demonstrated the ability to quickly surpass the US-dominant XBB.1.5 in terms of distribution. The new variant has shown a 188% growth advantage over it over the past three months, says Rajnarayanan.

And in India, where XBB created the last big wave, XBB.1.16 shows a 64% growth advantage, he adds.

Will the new Omicron COVID Booster protect me from XBB.1.16?

Such boosters should “provide some protection when the dose is new,” says Rajnarayanan, though the virus has evolved since they were released last fall.

Paxlovid keeps working, he adds. But when it comes to monoclonal antibodies, “the rest of the toolbox is useless,” he says.

Why should I still care about XBB.1.16 – or any other COVID variant?

A legitimate question, says Rajnarayanan: “With so much work, everyone is kind of tired and has given up.”

Unfortunately, it’s not safe to assume that therapeutics like the COVID antiviral Paxlovid, vaccines and tests will continue to work as virus evolution progresses, he warns.

“People want to know will vaccines work? Are there tools? Should I mask?” he says. However, the answers are subject to change and depend on which variants are in circulation and in what quantities.

It’s important to stay vigilant, he says.