As many as 90,000 Americans are projected to die from the coronavirus in the next four weeks, the new White House administration said Wednesday in its first science briefing on the COVID-19 pandemic.

The hourlong briefing by the team charged by President Joe Biden with ending the pandemic was meant to deliver on his promise of “leveling” with the American people about the state of the outbreak that has already claimed more than 426,000 U.S. lives.

Wednesday’s briefing was conducted virtually, rather than in person at the White House, to allow for questions from health journalists and to maintain a set timing no matter the situation in the West Wing. But it was not without technical glitches, according to The Associated Press.

It featured Jeff Zients, the Biden administration’s coordinator for pandemic response; his deputy, Andy Slavitt; Dr. Anthony Fauci, the nation’s top infectious disease expert; Dr. Marcella Nunez-Smith, the chair of Biden’s COVID-19 equality task force; and Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention.

“The White House respects and will follow the science, and the scientists will speak independently,” said Slavitt.

Zients, who previously ran the Obama administration’s efforts to salvage the rollout of HealthCare.gov used to sign up for Affordable Care Act insurance exchanges, repeated the federal government no longer has a stockpile of vaccines to distribute. He added the Biden administration was examining additional ways of speeding vaccine production, a day after the president announced the U.S. plans to have delivered enough doses for 300 million Americans by the end of summer.

“Most states are getting better at putting needles in arms,” said Zients, who called on Congress to swiftly act to pass Biden’s “American Rescue Plan.” The $1.9 trillion bill includes $400 billion for measures specifically aimed at controlling the virus, including dramatically increasing the pace of vaccinations and building out an infrastructure for widespread testing.

Zients added the federal Department of Health and Human Services acted Wednesday to make more professionals available to administer vaccinations. The government will authorize nurses and doctors who have retired to administer vaccines, and professionals licensed in one state will also be able to give shots in other states. Such measures are fairly standard in health emergencies.

Fauci told reporters there was reason to be concerned about the impact of some coronavirus mutations on vaccines, but that scientists have plenty of options for adjustments to maintain the effectiveness of vaccines and treatments.

Fauci said there was particular concern about the so-called South African variant because lab tests have shown that it can diminish the protective power of the vaccines approved to date. He stressed the level of protection provided was still well within what he called the “cushion” of vaccine effectiveness but added the government was working with pharmaceutical companies on potential “booster” shots for the new variants.

Walensky, the new head of the CDC, said her agency’s latest forecast indicates the U.S. will reach between 479,000 and 514,000 deaths by Feb. 20. More than 426,000 Americans have already died in the pandemic.

Dr. David Hamer, a professor of global health and medicine at Boston University’s School of Public Health, said having briefings from health officials that are “based on serious science” would go a long way toward improving public perceptions of the vaccine.

“There’s a certain amount of vaccine hesitancy, and so educating people about the vaccine, how it works, how safe it is and how it can protect against the disease but also slow transmission is really important,” he said.

The Associated Press contributed to this report.