President Joe Biden ordered flags lowered to half mast Monday after the United States crossed the "heartbreaking" milestone of 500,000 Covid-19 deaths, while Britain eyed lifting lockdowns in the latest sign of global gains against the pandemic.
An emotional Biden asked everyone to remain vigilant and urged maintain the hygiene practices.
Biden, accompanied by his wife Jill and Vice President Kamala Harris and her husband Doug Emhoff, then stood outside the White House to mark a moment's silence in front of 500 candles representing the toll -- the highest reported of any country.
But signs are also emerging that progress is being made both in the United States and around the world, with infections dropping sharply and vaccine deliveries rising steadily.
In Britain, Prime Minister Boris Johnson outlined a "gradual and cautious" approach to lifting curbs in England that could see life there return almost to normal by the end of June. The first step will be the return of children to schools from March 8.
Meanwhile, data from two separate studies published in the UK on Monday, one in England and another in Scotland, have shown vaccines against Covid-19 are effective in cutting disease transmission and hospitalisations from the first dose.
Analysis from Public Health England has shown the vaccine manufactured by Pfizer-BioNTech reduces the risk of catching infection by more than 70 percent after a first dose. That risk is reduced by 85 percent after a second dose.
Hospitalisation and death from Covid-19 is reduced by over 75 percent in those who have received a dose of the Pfizer-BioNTech vaccine, according to the analysis.
Meanwhile India, the world's second worst-hit nation in terms of infections, passed a bleak threshold on Monday by registering its 11 millionth case following a renewed rise in transmission. Fresh restrictions on gatherings came into force in the western state of Maharashtra, home to financial capital Mumbai, which has logged almost 52,000 deaths since the start of the pandemic.