Biden said he was stepping up the federal response to the virus including by taking steps to expand testing and vaccinations and increase mask-wearing.

“This is a wartime undertaking,” the Democratic president said at a White House event where he signed executive orders to establish a COVID-19 testing board to ramp up testing, address supply shortfalls, establish protocols for international travelers and direct resources to hard-hit minority communities.

The pandemic has killed 405,000 people and infected more than 24 million in the United States, the highest numbers anywhere in the world.

Former President Donald Trump, who left office on Wednesday, often sought to play down the severity of the country’s worst public health crisis in a century and left much of the planning to individual states, resulting in a patchwork of policies across the country.

Fauci, who served under Trump but has been promoted to Biden’s chief medical adviser, was at Biden’s side during the event and then spoke to reporters in the White House briefing room for the first time in weeks, after Trump largely banished him from the podium.

Fauci said he was “uncomfortable” at times during the Trump administration. He did not mention the Republican former president by name, but referred to comments about the drug hydroxycloroquine, which Trump boosted as a treatment for COVID-19 before its efficacy had been proven, which Fauci said “were not based on scientific fact.”