WASHINGTON (REUTERS) - US President-elect Joe Biden on Tuesday (Jan 19) led a national memorial observance on the eve of his inauguration to honour the 400,000 Americans who have died from Covid-19 during the 11 months since the novel coronavirus claimed its first US victim.

The sundown commemoration came just hours before President Donald Trump was due to depart the White House for the last time and hand over a country wracked by the greatest public health crisis in a century, economic devastation and violent political upheaval.

Ceremonies spearheaded by Mr Biden and Vice-President-elect Kamala Harris from the base of the Lincoln Memorial marked the federal government's first official nod to the staggering death toll from the pandemic.

"To heal, we must remember. It's hard sometimes to remember, but that's how we heal. It's important to do that as a nation," Mr Biden said to kick off a tribute that included observances in cities across the country.

As he spoke, 400 electric lamps lining the sides of the Reflecting Pool were illuminated to honour the 400,000 lives lost, followed by gospel singer Yolanda Adams' performance of the song "Hallelujah," then a moment of silence in memory of the Covid-19 dead.

A hospital nurse from Michigan, Ms Lori Marie Key, sang"Amazing Grace" before Mr Biden took to the podium. About 4 miles (6.5km) from where Mr Biden appeared, the bells of the National Cathedral were tolled 400 times after he spoke.

"Though we may be physically separated, we the American people are united in spirit," Ms Harris said before introducing Ms Key.

"My abiding prayer is that we emerge from this ordeal with a new wisdom - to cherish simple moments, to imagine new possibilities and to open our hearts just a little bit more to one another."

The United States surpassed 24 million Covid-19 infections and 400,000 lives lost from the virus on Tuesday, according to a Reuters tally.

The country has recorded more than 200,000 new cases and 3,220 deaths on average over the last seven days and has the highest COVID-19 death toll in the world.

The unrelenting loss of life has placed a particular strain on medical professionals on the pandemic's front lines.

"You're just surrounded by all of this horrible illness that you can't fix - all the time," said Dr Mangala Narasimhan, who oversees ICU teams for Northwell Health hospitals, New York state's largest healthcare provider.

"It's really a huge mental toll on the intensive care workforce, doing this day in and day out for almost a year now," she told Reuters.

Local officials from Miami to San Diego planned special lighting of prominent buildings for the Wednesday's ceremony.

Among the participating landmarks were the Empire State building in New York City and the Space Needle in Seattle, Mr Biden's inaugural committee said in a statement.

The committee also said it was encouraging Americans to light candles in their windows and churches to ring their bells in a show of unity.

The Cathedral of St. John the Divine in New York City was inviting the public to light a candle on its front steps on Tuesday evening before a solemn bell toll.

New chapter in pandemic response

The observance marked the beginning of a new era in the country's battle against Covid-19 under Mr Biden, who has pledged to make coronavirus relief a top priority when he takes office on Wednesday under unprecedented security measures in the nation's capital.

Mr Biden will inherit a grieving and sickened nation from Mr Trump, who critics say was to blame for a disjointed and ineffectual response to the pandemic, resulting in the United States suffering the highest Covid-19 national death toll in the world.

On Tuesday, his last full day as president, Mr Trump had no public events scheduled, although US Vice-President Mike Pence was planning to convene the White House Coronavirus Task Force for its last meeting under his watch.

Many of Mr Biden's policy plans fly in the face of the Trump administration's approach to combating the pandemic.

They include a mask mandate that would apply to federal properties, planes and buses and a recommitment to the World Health Organisation after Mr Trump's withdrawal from the agency.

Mr Biden will also face the daunting task of overseeing the nation's Covid-19 vaccine distribution and administration. The United States is trailing in its vaccination goal, with only 12.3 million shots administered out of more than 31 million distributed as of Jan 15, according to the Centres for Disease Control and Prevention.

States, tasked with rolling out their own vaccine programmes, have lamented a lack of funding and support from the federal government. Some localities say they do not have adequate supply to meet demand.

The mayors of New York City and San Francisco warned on Tuesday they expect to run out of vaccine doses this week unless new shipments are forthcoming.

California, which has emerged as the leading US epicentre of the pandemic in recent weeks, offered a glimmer of optimism on Tuesday after State Health Secretary Dr Mark Ghaly said hospitalisation rates were levelling off in a sign that a surge of cases spurred by the year-end holiday was beginning to ease.

Steeply rising infections have pushed hospital emergency rooms, intensive care units, ambulance bays and morgues to overflowing during the past month, especially in and around Los Angeles.

Dr Ghaly said caseloads are expected to keep rising over the next two weeks but not as quickly as officials had feared, a sign that restrictions on business and social activities were working.

"There are rays of hope shining through," he said in a briefing with reporters.