Barack Obama has called for US citizens to use “common sense” in avoiding the spread of coronavirus following reports of new cases.

The former US president took to Twitter to give simple but timely advice urging members of the public to wash their hands and listen to health experts.

Mr Obama also addressed the panic-buying of face masks as concerns over shortages of protective health equipment for medical workers increase.

He tweeted on Wednesday: “Protect yourself and your community from coronavirus with common sense precautions: wash your hands, stay home when sick and listen to the Centres for Disease Control and Prevention and local health authorities.

“Save the masks for health care workers,” he added. “Let’s stay calm, listen to the experts and follow the science.”

The World Health Organisation called on governments and industry to increase production of masks and gloves for health workers as stocks globally are running low.

Authorities all over the world are dealing with hoarding of masks, gloves, and sanitising gel as fears of getting infected are heightened.

Mr Obama’s advice comes as the number of coronavirus cases in the US has risen sharply to more than 120, with 11 deaths.

California declared a state of emergency afters its first coronavirus fatality, which was also the first in the US outside Washington state.

A cruise ship that previously carried two passengers who contracted coronavirus was barred from returning to San Francisco on Wednesday after at least 20 passengers complained of symptoms consistent with the virus.

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California’s governor, Gavin Newsom, said the cruise ship, Grand Princess, would remain at sea while coronavirus testing kits are flown out and flown back with samples for analysis.

Around 1,000 people in New York have been asked to self-quarantine after city officials confirmed five more people were infected and they were searching for anyone who had close contact with them.

According to CNN, cases have also been detected in Arizona, Florida, Georgia, Illinois, Massachusetts, New Hampshire, North Carolina, Oregon, Rhode Island and Wisconsin.

The US House of Representatives on Wednesday overwhelmingly approved an US$8.3 billion bill to combat the spread of the virus and develop vaccines.

Health officials warned the number of cases in the US will continue to climb, but called for people not to panic as “we knew this was coming”.

The surgeon general, Jerome Adams, said on Monday: “I want folks to understand that we knew this was coming, we told folks it was going to happen and it is why we’ve been preaching preparedness from the very start.