More than 25 million Covid-19 cases have been recorded in the United States since the pandemic began, Johns Hopkins University said Sunday, just days after President Joe Biden's inauguration.
The milestone was reached only five days after the US, the world's wealthiest and hardest-hit nation, recorded 400,000 deaths from the disease.
Biden has made fighting the coronavirus a priority and is pushing for Congress to approve a $1.9-trillion relief package that would include billions of dollars to boost vaccination rates.
Biden has said he wants 100 million people vaccinated within his first 100 days in office, and he has called for Americans to wear masks for 100 days.
Countries around the world are in a race against time to get their populations inoculated before the coronavirus mutates into a strain that could resist newly approved vaccinations.
Vivek Murthy, Biden's nominee for surgeon-general, told ABC News on Sunday that 100 million doses in 100 days was "a floor, not a ceiling" and cautioned about new strains.
"The variants are very concerning," Murthy told the network.
"It's up to us to adapt and stay ahead," he added.
The US caseload remains by far the highest in absolute terms.
India, where the population is about four times larger than in the US, has the second-highest caseload with about 10.6 million cases, according to Johns Hopkins.
After the first Covid-19 case was reported in the US in January 2020 it took until late April for the figure to pass one million. The overall number of cases has followed an almost exponential curve upwards since then.
Last week, Baltimore-based Johns Hopkins announced more than 400,000 people in the US had died from Covid-19, a grim marker that came one day before Biden's inauguration.