The fear of new COVID variants is adding a sense of trepidation to America’s latest great reopening.

Driving the news: While cases and hospitalizations are plummeting worldwide after massive Omicron-fueled surges, the spread of an even more transmissible Omicron subvariant is making some experts nervous as states lift mask mandates and other restrictions.

“The bottom line is we’re relatively optimistic that things will continue to improve through the spring and the summer under Omicron,” Matt Craven, a partner at McKinsey who specializes in public health and infectious disease, said Wednesday during a U.S. Chamber of Commerce event. 

• But this new subvariant “serves as that reminder we very well may not be done here and there may be others coming,” he said.

State of play: This week, the World Health Organization reiterated the subvariant, dubbed BA.2, is a “variant of concern” while also saying it would continue to be classified as Omicron.

• Health officials are examining whether BA.2 may slow declines or even cause an increase in cases, WHO epidemiologist Maria Van Kerkhove told the Wall Street Journal.

Between the lines: Thus far, it’s believed the Omicron subvariant is more transmissible — roughly 30% more than the original strain, WHO reported — but may not cause more severe disease than the original Omicron strain. 

• A preprint study out of Japan, which used animals with no immunity to COVID-19, indicated the BA.2 subvariant had features that make it capable of causing more severe illness. 
• However, several real-world data from pre-print studies, including one from South Africa, where immunity from vaccination or natural infection is high, has found “no difference in severity” between the original Omicron and the subvariant.
• A pre-print study from Denmark found the subvariant is capable of reinfecting individuals who’d recently had COVID-19 from the Omicron or Delta strains, though the phenomenon was not common.

Yes, but: Additional pre-print studies from Columbia University and NYU based on laboratory data indicate a COVID treatment, the antibody sotrovimab, could be less effective against the variant.

• “With monoclonal antibodies, we’re trying to hit a moving target,” says David Ho, a virologist at Columbia University in New York City and a co-author of one of the studies told the science journal Nature.

The big picture: “As of now, I don’t think that we need to sound a global alarm. But I do think that we need to pay attention,” Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston told CNN.