The global Covid-19 death toll has risen past one million, however there are warnings the figure is likely to underestimate the true total.
UN Secretary-General António Guterres called it a "mind-numbing" figure and "an agonising milestone".
"Yet we must never lose sight of each and every individual life," he said in a video message.
"They were fathers and mothers, wives and husbands, brothers and sisters, friends and colleagues. The pain has been multiplied by the savageness of this disease. Risks of infection kept families from bedsides. And the process of mourning and celebrating a life was often made impossible.”
Mr Guterres warned “there is no end in sight to the spread of the virus, the loss of jobs, the disruption of education, the upheaval to our lives”.
But he said the pandemic could be overcome with responsible leadership, co-operation and science, as well as precautions such as social distancing and wearing face masks.
He said any vaccine must be “available and affordable to all”.
The official toll draws on information from the World Health Organisation (WHO), the US and European centres for disease prevention and control and China’s national health authority, among other sources.
But experts cautioned the tally probably underestimates the true total, with a senior WHO official cautioning on Monday that the actual number of Covid-19 deaths is probably much higher.
“If anything, the numbers currently reported probably represent an underestimate of those individuals who have either contracted Covid-19 or died as a cause of it,” Mike Ryan, the WHO’s top emergencies expert, told a briefing in Geneva.
“When you count anything, you can’t count it perfectly but I can assure you that the current numbers are likely an underestimate of the true toll of Covid.”
To date, deaths in the United States, Brazil and India, which is currently recording the most new cases per day, have made up nearly half the total recorded worldwide. The US has recorded 205,000 fatalities, with Brazil and India registering 141,700 and 95,500 respectively.
The pandemic has also now spread to 188 countries, with more than 33 million confirmed cases, prompting widespread lockdowns and unleashing devastating economic downturns.
But the figures only mark the known toll of a virus that may have already been spreading globally, and killing people, before it was first identified in China in December last year.
Studies undertaken in Italy found traces of the virus in sewage samples taken at that time, while scientists in France have identified a case there on 27 December, meaning Covid-19 may have arrived in Europe almost a month earlier than previously thought.
Meanwhile, there is thought to be a significant underreporting of deaths in many countries either for political reasons or due to lack of capacity.
Amid the ongoing surge in new infections, efforts to develop an effective vaccine are continuing - although the WHO has cautioned the global death toll could reach two million before one is widely available.
Globally there are some 240 potential vaccines in early development, with 40 in clinical trials and nine in the final stage of testing on thousands of people.
Vaccine development typically takes years but owing to the ongoing global emergency sparked by coronavirus, scientists are working at breakneck speed to produce an inoculation.