The Arab uprisings a decade ago were supercharged by online calls to join the protests -- but the internet was soon flooded with misinformation, weakening the region's cyber-activists.

When Tunisian dictator Zine El Abidine Ben Ali fled the country in January 2011, rumours and uncertainty created "panic and hysteria", said ex-activist and entrepreneur Houeida Anouar.

"January 14 was a horrible night, so traumatic," she said. "We heard gunfire, and a neighbour shouted 'hide yourselves, they're raping women'."

As pro-regime media pumped out misinformation, the flood of bogus news also spread to the internet, a space activists had long seen as a refuge from censorship and propaganda.

The United States is the worst-affected country, with 266,074 Covid-19 deaths, and President Donald Trump's administration has issued conflicting messages on mask-wearing, travel and the danger posed by the virus.

"There almost certainly is going to be an uptick because of what has happened with the travel," Fauci told CNN's "State of the Union."

Travel surrounding Thursday's Thanksgiving holiday made this the busiest week in US airports since the pandemic began.

"We may see a surge upon a surge" in two or three weeks, Fauci added. "We don't want to frighten people, but that's the reality."