The United States on Monday crossed the staggering milestone of 500,000 COVID-19 deaths just over a year since the coronavirus pandemic claimed its first known victim in Santa Clara County, California. In a proclamation honoring the dead, President Joe Biden ordered the U.S. flag to be flown at half-staff on public buildings and grounds until sunset on Friday. “On this solemn occasion, we reflect on their loss and on their loved ones left behind,” Biden said in the proclamation. “We, as a Nation, must remember them so we can begin to heal, to unite, and find purpose as one Nation to defeat this pandemic.” Bells tolled at the National Cathedral in Washington to honor the lives lost - ringing 500 times to symbolize the 500,000 deaths. “As we acknowledge the scale of this mass death in America, remember each person and the life they lived,” Biden said in a somber speech at the White House after the bells sounded. “The son who called his mom every night just to check in. The father, the daughter who lit up his world. The best friend who was always there. … The nurse who made her patients want to live.” A few moments later, Biden, Vice President Kamala Harris and their spouses appeared wearing black clothing and black masks. They stood silently as the hymn “Amazing Grace” was played. The country had recorded more than 28 million COVID-19 cases and 500,264 lives lost as of Monday afternoon, according to a Reuters tally of public health data, although daily cases and hospitalizations have fallen to the lowest level since before the Thanksgiving and Christmas holidays. About 19% of total global coronavirus deaths have occurred in the United States, an outsized figure given that the nation accounts for just 4% of the world’s population. “This is the worst thing that’s happened to this country with regard to the health of the nation in over 100 years,” Dr. Anthony Fauci, a top infectious disease adviser to President Joe Biden, said in an interview with Reuters on Monday. He added that decades from now, people would be talking about “that horrible year of 2020, and maybe 2021.” For most of 2020, Fauci served on former President Donald Trump’s White House Coronavirus Task Force, a job that often put him at odds with Trump, who sought to downplay the severity of pandemic despite contracting COVID-19 himself, and refused to issue a national mask mandate. Political divisiveness, Fauci said, contributed significantly to the U.S. death toll. MORE VIGILANCE URGED The country’s poor performance reflects the lack of a unified, national response last year, when the administration of former President Donald Trump mostly left states to their own devices in tackling the greatest public health crisis in a century, with the president often in conflict with his own health experts. In 2020, the virus has taken a full year off the average life expectancy in the United States, the biggest decline since World War Two. Sweeping through the country at the beginning of last year, the U.S. epidemic had claimed its first 100,000 lives by May. The death toll doubled by September as the virus ebbed and surged during the summer months. Pandemic-weary Americans, like so many around the world, grappled with the mountain of loss brought by COVID-19 as health experts warned of yet another coronavirus resurgence during the fall and winter months. Americans lost mothers and fathers, husbands and wives, brothers, sisters and friends to the virus. For many, the grief was amplified by the inability to see loved ones in hospitals or nursing homes and by the physical distancing imposed by authorities to curb the virus spread. By December, the death toll had reached 300,000 in the United States. In the three months after Thanksgiving, the virus would claim 230,000 lives. With numbers that made the appalling toll early in the pandemic pale by comparison, deaths recorded between December and February accounted for 46% of all U.S. COVID-19 fatalities, even as vaccines finally became available and a monumental effort to inoculate the American public got started. Despite the grim milestone, the virus appears to have loosened its grip as COVID-19 cases in United States fell for the sixth consecutive week. Health experts have warned, however, that coronavirus variants initially discovered in Britain, South Africa and Brazil could unleash another wave that threatens to reverse the recent positive trends. In his White House remarks, Biden called on Americans to remain vigilant in fighting the pandemic by continuing to wear masks, observe social distancing and receive vaccinations when it is their turn.