WASHINGTON, Jan. 7 (REUTERS) -- COVID-19 hospitalisations in the United States are poised to hit a new high as early as Friday (Jan 7), according to a Reuters tally, surpassing the record set in January of last year as the highly contagious Omicron variant fuels a surge in the number of cases.

Hospitalisations have increased steadily since late December as Omicron quickly overtook Delta as the dominant strain of the coronavirus in the United States, although experts say Omicron will likely prove less deadly than prior variants.

While deemed less severe, health officials have nevertheless warned that the sheer number of infections caused by Omicron could strain hospital systems, some of which have already shown signs of distress, partly due to staffing shortages.

"I don't believe we've seen the peak yet here in the United States," Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky told NBC News' Today program on Friday, as schools and businesses also struggle with rising caseloads.

Walensky also said that the CDC has not yet seen a signal that the Omicron variant is more severe in young children despite an increase of the hospitalisations.

"We have not yet seen a signal that there is any increased severity" in kids under 5, who are not yet eligible for vaccination, Walensky said. She said that an increase in cases in general could be one explanation for the surge in hospitalisations.

In a report released on Friday, the CDC said that two doses of the Pfizer-BioNTech COVID-19 vaccine are highly protective against Multisystem Inflammatory Syndrome in Children (MIS-C). MIS-C causes inflammation in children in organs including the heart, lungs, kidneys and brain two to six weeks after a mild or asymptomatic infection.