The explosive increase in US coronavirus case counts is raising alarm, but some experts believe the focus should instead be on Covid-19 hospital admissions. And those aren't climbing as fast.

Dr Anthony Fauci, for one, said Sunday on ABC that with many infections causing few or no symptoms, "it is much more relevant to focus on the hospitalisations as opposed to the total number of cases". Other experts argue that case counts still have value.

As the super-contagious omicron variant rages across the US, new Covid-19 cases per day have more than tripled over the past two weeks, reaching a record-shattering average of 480,000. Schools, hospitals and airlines are struggling as infected workers go into isolation.

Meanwhile, hospital admissions averaged 14,800 per day last week, up 63% from the week before, but still short of the peak of 16,500 per day a year ago, when the vast majority of the US was unvaccinated. Deaths have been stable over the past two weeks at an average of about 1,200 per day, well below the all-time high of 3,400 last January.

Public health experts suspect that those numbers, taken together, reflect the vaccine's continued effectiveness at preventing serious illness, even against omicron, as well as the possibility that the variant does not make most people as sick as earlier versions.