In a statement, Biden acknowledged the loss’ impact on families left behind and urged the country not to “grow numb to such sorrow,” noting “a nation forever changed.”

The United States on Wednesday recorded more than 1 million COVID-19 deaths, according to a Reuters tally, crossing a once-unthinkable milestone about two years after the first cases upended everyday life. The loss represents about one death for every 327 Americans, or more than the entire population of San Francisco or Seattle.

Biden will mark the grim milestone by ordering flags to be flown at half-staff, said the White House, which will on Thursday also host a second global COVID Summit.

The Democratic president has urged Congress to fund billions more in COVID aid to continue fighting the virus as new variants emerge, but this week decoupled the request from separate Ukraine aid that is set to pass in the coming days.

“We must remain vigilant against this pandemic and do everything we can to save as many lives as possible, as we have with more testing, vaccines, and treatments than ever before,” Biden said on Thursday. “It’s critical that Congress sustain these resources in the coming months.”

U.S. lawmakers had reached a $10 billion deal but the additional tranche of funding has been delayed over various concerns.

Researchers are working on yet another booster shot as the virus continues to mutate, and health experts have said greater pandemic investment is needed now to thwart future outbreaks that could cause further havoc.

The precise toll of the pandemic may never be truly known. Some people who died while infected were never tested and are not represented in the data. Others, while having COVID-19, may have died for another reason such as a cancer, but were still counted.

(Reporting by Trevor Hunnicutt, Writing by Alexandra Alper and Susan Heavey; Editing by Bradley Perrett and Bernadette Baum)