WASHINGTON: Faced with a doubling of Covid hospitalizations in recent months, US health authorities reiterated the need Tuesday for vaccine vigilance to fight the pandemic, even as the jabs’ immunity against new Omicron subvariants remains unclear.

The United States is recording some 5,100 coronavirus-related hospitalizations per day, “a doubling of hospital admissions since early May,” Center for Disease Control and Prevention (CDC) Director Rochelle Walensky told a press briefing.

The increase is linked to the meteoric rise of the Omicron variant’s BA.4 and BA.5 sublineages, which were first detected in April and which respectively represent 16 percent and 65 percent of the virus currently circulating in the United States.

While they do not appear to be more severe than previous variants, “we do know it to be more transmissible and more immune-evading,” Walensky said, although she added that vaccination and booster effectiveness against severe illness and death likely remains high with the new variants.

“So staying up to date on your Covid-19 vaccines provides the best protection against severe outcomes,” she said.

Despite the rise in cases, the new variants should not be allowed to cause panic or “disrupt our lives,” President Joe Biden’s chief medical advisor Anthony Fauci told the briefing.

While daily tolls have reduced substantially since the crisis peaked more than a year ago, the United States is still recording 300 to 350 deaths per day, an “unacceptable” number, Fauci said.

The country is seeing between 100,000 and 150,000 new reported cases daily, but the figure could be substantially underestimated due to the expansion in use of home Covid tests, whose results are often not reported to authorities.