A new coronavirus variant, EG.5, now accounts for the largest proportion of Covid infections in the U.S., according to estimates from the Centers for Disease Control and Prevention.

Over a two-week period ending on Saturday, EG.5 — which some health experts on social media nicknamed “Eris” — made up an estimated 17.3% of new cases nationwide. That’s up from just under 12% during the prior two-week period, and less than 1% as of late May.

EG.5, like the other strains that have gained dominance in the U.S. over the last year-plus, is a subvariant of omicron. More precisely, it’s considered a descendant of the XBB lineage of the virus. After EG.5, the next most common subvariant, XBB.1.16, accounts for just over 15% of new cases, while XBB.2.23 makes up around 11%.

Globally, EG.5 accounted for 11.6% of weekly cases in mid-July, up from 6.2% four weeks earlier, according to the World Health Organization. The WHO has categorized it as a variant under monitoring, which is a step below variants of interest or concern.

The U.K. began monitoring for EG.5.1 — a descendant within the larger EG.5 umbrella — in July, according to the U.K. Health Security Agency. As of July 20, the variant made up 14.5% of cases there.

The spread of EG.5 comes as the U.S. logs its first increase in hospitalizations of the year. More than 9,000 people were hospitalized with Covid in the last week of July, up from about 6,300 at the end of June.

However, three experts interviewed for this story said there is not yet evidence that EG.5 is responsible for the rise in hospitalizations. Plus, they said, this summer’s hospitalization rates are still relatively low, and far below the December 2022 peak of over 44,000 weekly Covid hospitalizations.

Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, said there is no evidence that EG.5 infections cause more severe illness than other omicron subvariants.

EG.5 has likely evolved to become more transmissible than its predecessors, however, as evidenced by its prevalence, Barouch said. But he suggested that widespread immunity from a combination of vaccinations and past infections should keep most people safe from severe illness.