Covid-19 case counts in the U.S. reached record highs as the Omicron wave extended its reach through communities across the country.

The seven-day average for new cases reached about 663,700 by Friday evening, according to Johns Hopkins University. Hospitalizations have been surging and are nearing record-high levels, federal data show, reflecting both the high level of people with Covid-19 needing care and the many testing positive after they are admitted for other reasons.

Centers...

Covid-19 case counts in the U.S. reached record highs as the Omicron wave extended its reach through communities across the country.

The seven-day average for new cases reached about 663,700 by Friday evening, according to Johns Hopkins University. Hospitalizations have been surging and are nearing record-high levels, federal data show, reflecting both the high level of people with Covid-19 needing care and the many testing positive after they are admitted for other reasons.

Centers for Disease Control and Prevention Director Rochelle Walensky on Friday noted a rise in hospitalizations among children. She said some of the children were asymptomatic and tested positive after coming to hospitals for something else.

Data tracking the pandemic are still shaking off the effects of holiday reporting disruptions, which depress numbers as health departments slow reporting and then show higher numbers as they catch up. The seven-day case average on Friday jumped more than 61,000 from the prior day, for example, because it no longer includes a depressed number from New Year’s Eve. Los Angeles County alone reported 43,000 new cases on Friday, the latest in a string of daily records.

Some officials have said they have hope that Omicron will lead to a rapid crest in cases, given the extremely fast spread of infections racing through communities. In hard-hit New York City there are signs the pace of the case surge may at least be easing.

“In the last few days what we’re seeing is that the steepness of the curve is not quite as much,” Dave Chokshi, commissioner of the New York City Department of Health and Mental Hygiene, said during a press conference Wednesday. He said it would take time to see whether this was a real pattern or related to testing patterns, and that infections stemming from New Year’s gatherings were still a risk factor.

The U.S. by Friday was reporting about 1,550 Covid-19 deaths a day, the seven-day average from Johns Hopkins data shows. This increased nearly 300 from the report a day earlier, also a possible artifact of the average moving on from including data during the holiday slowdown. Public-health experts have said it would still take time to know the extent to which this Omicron-fueled Covid-19 case surge translates into deaths, which are a lagging indicator.

Write to Jon Kamp at jon.kamp@wsj.com