The latest coronavirus surge sweeping the United States, much of it driven by the highly contagious Omicron variant, has produced a worrisome rise in hospitalizations among children, not to mention heightened anxiety among parents nationwide.

Several states have reported increases of about 50 percent in pediatric admissions for Covid-19 in December. New York City has experienced the most dramatic rise, with 68 children hospitalized last week, a fourfold jump from two weeks earlier.

But even as experts expressed concern about a marked jump in hospitalizations — an increase more than double that among adults — doctors and researchers said they were not seeing evidence that Omicron was more threatening to children.