Pfizer's anti-Covid pill Paxlovid is helping stave off hospitalizations and deaths amid the United States' latest wave of infections, a senior White House official said Wednesday.

Demand for the treatment has soared, with a four-fold increase over the past month and an estimated 20,000 prescriptions being written every day, White House Covid-19 Response Coordinator Ashish Jha told reporters in a press call. 

"I think that is actually a really important reason why, despite this very substantial increase in infections, we have not seen a commensurate increase in deaths," he said. 

"We have seen hospitalizations rise, but again, not as much as one would have expected at this point, despite the fact that hospitalizations do lag. When you look at ICU care, the rate of ICU hospital admissions is much lower than what one would expect."

President Joe Biden's administration last month embarked on an aggressive push to expand access to the oral antiviral at tens of thousands of locations across the country.

Omicron's subvariants have driven daily new cases to 94,000, a three-fold increase over the last month, with hospitalizations running at 3,000 a day, and deaths at around 275.

Paxlovid, a combination of two drugs, both taken orally over five days, was shown in a clinical trial to reduce hospitalizations and deaths among at-risk people by almost 90 percent.

Concerns have been raised about "Paxlovid rebound" -- in which some patients clear the virus while on the treatment, but test positive after completing their course.

Jha said the government was studying the issue closely, "but I think it is not leading to people getting particularly sick." The rate of rebound during Paxlovid's clinical trial was two percent, but the dominant variant at the time was Delta.

He also encouraged doctors to adopt a "relatively permissive" approach to prescribing the medicine, given the broad eligibility criteria for being high risk.

"You should not get excessively restrictive, we have plenty of supply right now," he advised doctors.

Jha also urged Congress to quickly provide $22.5 billion in Covid funding so that the government could ensure the supply of next generation Covid vaccines, which are expected to protect against multiple variants.

"Other countries are in conversations with the manufacturers and starting to advance their negotiations," he said, warning Americans could be left behind.

If Congress failed to provide funding, "I think it'd be terrible, I think we'd see a lot of unnecessary loss of life if that were to happen," he said, but the Biden administration would try to find a way to provide vaccines to those at highest risk, he added.