WHO Upgrades XBB.1.16 to a ‘Variant of Interest’ as Cases Rise in the U.S.
The arcturus subvariant behind a COVID-19 surge in India has been reported in 31 countries and 18 U.S. states.
Editor’s Note
The World Health Organization (WHO) has elevated the omicron subvariant XBB.1.16 to a “variant of interest,” according to its weekly COVID-19 report on April 20. Dubbed arcturus by those tracking the virus, XBB.1.16 continues to fuel a surge of cases in India, where it’s the dominant subvariant, and has been identified in at least 31 countries, including the United States. Despite the increasing case numbers, the organization said that “at present, there is no early signal of an increase in severity” of symptoms.
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XBB.1.16 is “one to watch,” according to Maria Van Kerkhove, PhD, the COVID-19 technical lead at WHO and a professor at the Georgetown University Center for Global Health Science and Security in Washington, DC.
WHO is actively monitoring XBB.1.16, Dr. Van Kerkhove said at a press conference on March 29, “because it has potential changes that we need to keep a good eye out on.”
“It’s actually very similar in profile to XBB.1.5. It has one additional mutation in the spike protein, which in lab studies shows increased infectivity, as well as potential increased pathogenicity” (the potential to produce disease), she said.
The subvariant XBB.1.5 is currently responsible for almost 80 percent of COVID-19 cases in the United States, according to the COVID Data Tracker from the Centers for Disease Control and Prevention (CDC).
XBB.1.16 has been reported in at least 18 U.S. states, according to the Journal of Urgent Care Medicine, and case counts have nearly doubled for the second week in a row, accounting for an estimated 9.6 percent of current cases — although the number could be as high as 13.6 percent, according to the latest estimates from the CDC.
“This appears to be a highly communicable variant, based on reports from around the world,” says Paul Pottinger, MD, a professor in the division of allergy and infectious diseases at UW Medicine in Seattle.
Why Are Health Officials Concerned About XBB.1.1.6?
One of the big uncertainties around COVID-19 is that the virus hasn’t settled into a predictable pattern and continues to evolve, said Van Kerkhove at the press conference. “One of things we are very concerned about is the potential for the virus to change, to become not only more transmissible but more severe,” she said.
There will continue to be waves of COVID infection, said Van Kerkhove. “The peaks of those infections may not be as large as we saw before and likely will not be, because we have population-level immunity that has increased around the world from vaccination and also from past infection,” she said.
India has reported more than 120,000 new COVID-19 cases in the past 28 days, compared with about 10,000 in the previous four weeks, according to the April 20 WHO report. The country’s health ministry is conducting mock drills to check preparedness of hospitals to deal with rising COVID-19 numbers, according to a BBC report.
Although case counts in India are still relatively low compared with previous surges, deaths and hospitalizations caused by the new subvariant continue to climb.
“Indian COVID surge: Severity of cases is going up in Delhi too! XBB.1.16 #Arcturus effect? Hospitalization count: 170 (66 in ICU, 54 on oxygen support and 15 on Ventilator)” read an April 11 tweet by Vipin Vashishtha, MD, a pediatrician at Mangla Hospital in Bijnor, India, and a former head of the Indian Academy of Pediatrics Committee on Immunization.
Testing, Antivirals, and Vaccination Continue to Play an Important Role in Preventing COVID-19 Transmission
People older than 60 and those with underlying health conditions continue to have the highest risk of severe COVID-19, said Van Kerkhove.
Healthcare systems need to “have good antivirals that are in use and given to patients who need them, when they need them, to prevent severe disease and really, critically, to focus on vaccinating those who are most at risk,” she said.
COVID-19 testing still detects this subvariant quite well, so people who think they may have been infected should be tested, says Dr. Pottinger.
If you’re not yet fully vaccinated and boosted, the new subvariant is “another good reason to get that taken care of,” he says.
“We do not know whether this variant may be more or less virulent than other strains, meaning the severity of illness that it causes is not yet fully described, but I am hopeful it will be a mild course for most patients,” says Pottinger.
As with earlier variants, people with chronic medical issues, especially those who have lung issues or are immunocompromised, may still be at risk of more severe illness, he says.
“So far, it appears that Paxlovid remains effective in reducing the duration of viral shedding for this variant, and thus it is likely beneficial for patients in those high-risk categories,” says Pottinger.