Global coronavirus infections passed 65 million on Friday and countries doubled down on restrictions, even as plans to roll out vaccines gathered pace.
Joe Biden said he would ask Americans to wear masks for 100 days when he takes over as president of the United States, the world's worst-hit country from a pandemic that has now killed more than 1.5 million people across the planet.
"I'm going to ask the public for 100 days to mask. Just 100 days to mask -- not forever," Biden told CNN on Thursday.
The US is among the countries posting all-time highs in daily deaths this week along with Italy, which is undergoing a dramatic resurgence after it largely tamped down its earlier outbreak by enforcing a strict lockdown in the spring.
The alarming spikes come after more positive news on vaccine development, with US-based Moderna announcing its candidate drug confers immunity for at least three months.
To build trust in vaccines after they are approved, 78-year-old Biden said he was willing to be vaccinated in public -- following up on similar commitments from former US presidents Barack Obama, George W. Bush, and Bill Clinton.
Biden also used the CNN interview to say he had asked the government's top infectious disease specialist Anthony Fauci to join his Covid team and serve as a chief medical adviser.
But in a sign of the difficult work ahead, California announced new statewide bans on gatherings and non-essential activities, as hospitals in the nation's most populous state face being overwhelmed.
- Vaxx hack -
The pandemic is showing little sign of slowing, with the daily global death toll in recent weeks reaching its highest rate since the virus emerged in China late last year.
However, the rapid development of several vaccines has provided respite from the dismal cycle of lockdowns and surging cases.
Britain on Wednesday became the first Western country to approve a vaccine for general use, piling pressure on other countries to swiftly follow suit.
But Fauci said Britain had rushed its approval process.
"In all fairness to so many of my UK friends, you know, they kind of ran around the corner of the marathon and joined it in the last mile," he told CBS, although he later said he had not meant to imply "any sloppiness".
Britain's regulator hit back on Friday, saying: "No vaccine would be authorized for supply in the UK unless the expected standards of safety, quality and efficacy are met."
Other nations are also moving ahead with plans to roll out the vaccines. Belgium and France have said jabs would begin in January for the most vulnerable.
But officials were not the only ones to focusing on vaccines.
IBM said on Thursday that hackers had targeted companies involved in the effort to distribute doses around the world.
The firm said it was not sure if the cyberattacks had been successful or who was behind them, but the precision of the operation had "the potential hallmarks of nation-state tradecraft".
- '12th man back' -
UN Secretary-General Antonio Guterres warned that even if vaccines were quickly approved, the world would still be fighting the pandemic's aftershocks.
"Let's not fool ourselves. A vaccine cannot undo damage that will stretch across years, even decades to come," Guterres said while opening a special UN summit on the virus.
The worlds of sport and culture are still grappling with the pandemic's society-altering effects.
On Thursday, Warner Bros. studio said it would release its entire 2021 schedule of movies on HBO Max streaming and in theatres simultaneously -- a paradigm shift for the cinema industry.
And the organizers of the Tokyo Olympics, which will take place one year later than planned, said Friday the postponement would inflate its already bloated budget by a further $2.4 billion.
But some English football supporters were given a reminder of pre-pandemic days as Arsenal welcomed a crowd of 2,000 for Thursday's Europa League win over Rapid Vienna.
It was the first time in 270 days that fans were back inside a Premier League ground.
"It's just great to have that sound back and have our 12th man back," said Arsenal midfielder Ainsley Maitland-Niles.