The United States is facing a dark milestone this week despite a recent decline in COVID-19 cases as it prepares to mark a staggering half a million deaths, with President Joe Biden planning to memorialise the lives lost.
While the number of cases fell for the fifth consecutive week and officials scrambled to inoculate the population, the nation was poised to reach 500,000 deaths from the highly infectious respiratory disease.
It has been nearly a year since the pandemic upended the country with duelling public health and economic crises.
"It's nothing like we've ever been through in the last 102 years since the 1918 influenza pandemic. ... It really is a terrible situation that we've been through - and that we're still going through," Dr. Anthony Fauci, White House COVID-19 medical adviser and the nation's top infectious disease official, told CNN on Sunday.
The White House said it planned a memorial event in which Biden would deliver remarks.
A White House spokesman said the president along with first lady Jill Biden, Vice President Kamala Harris and second gentleman Doug Emhoff would hold a moment of silence on Monday and there would be a candle-lighting ceremony at sundown.
More than 28 million cases have rocked the US and 497,862 have died, even as daily average deaths and hospitalisations have fallen to the lowest levels since before the Thanksgiving and Christmas holidays.
The virus has taken one full year off the average life expectancy in the US, the biggest decline since World War II.
Fauci told CNN that Americans may still need masks in 2022 even as other measures to stop the virus' spread become increasingly relaxed and more vaccines are administered, and they may also need a booster shot depending on how variants emerge.
Less than 15 per cent of the US population has received at least one vaccine dose, with nearly 43 million getting at least one shot and nearly 18 million getting a second shot, statistics show.
More localities are easing some restrictions, such as on indoor dining, and moving to reopen schools even as millions await their shots, sparking debate over the safety of teachers, students and others.
Financial pressures also continue to weigh even as economists express optimism for the year ahead. Congress is weighing Biden's $US1.9 trillion ($A2.4 trillion) coronavirus relief package, with the House of Representatives expected to vote on it this week and the Senate seeking to pass it before March 14.