Taylor Swift. (Reuters photo)

Action star Arnold Schwarzenegger told Americans to "ignore the morons", Lady Gaga said she was staying at home with her dogs, and Taylor Swift said sacrifices are needed as she urged her 128 million fans to practise social distancing in a bid to contain the coronavirus.

As US authorities stepped up calls for Americans to move beyond hand washing and isolate themselves as much as possible, Ariana Grande and Heidi Klum added their voices to celebrities appealing for drastically reduced social interactions.

"I'm seeing lots of get-togethers and hangs and parties still happening. This is the time to cancel plans, actually truly isolate as much as you can," Swift posted on social media on Sunday.

"It's a really scary time, but we need to make sacrifices right now," the Fearless singer said.

New York and Los Angeles announced closures of bars, movie theatres and restaurants starting on Monday, as the death toll from the outbreak rose to 65 over the weekend.

Schwarzenegger, the Terminator star and former California governor, posted video of himself at his kitchen table hugging his two miniature horses.

"We don't go out. We don't go to restaurants. We don't do anything like that anymore here," he said on Sunday. "Stay at home as much as possible. Listen to the experts, ignore the morons."

Pop star Grande appeared to be responding to social media postings at the weekend of people bragging about frequenting bars, restaurants and public places in spite of the coronavirus outbreak.

"It is incredibly dangerous and selfish to take this situation that lightly," the 7 Rings singer with 177 million Instagram followers posted. "Please don't turn a blind eye."

Former Bond girl Olga Kurylenko, who appeared in Quantum Of Solace in 2008, announced on Sunday that she was "locked up at home" after testing positive for coronavirus, joining Tom Hanks and his wife Rita Wilson as celebrities who have been diagnosed with the disease.

Model and America's Got Talent judge Heidi Klum said she was keeping apart from her musician husband Tom Kaulitz after coming down with a fever a week ago. Klum said she has tested for coronavirus but has not provided an update on the result.

"As much as I want to embrace him and kiss him, it is more important to do the right thing and not spread further," Klum posted on Instagram.

Singer Miley Cyrus appealed to fans to stop panic buying and hoarding and to be thoughtful while preparing for social distancing. "NO ONE needs every soup in the store," she wrote on Twitter.