Health chiefs warned of months of worldwide disruption from COVID-19 on Thursday as Italy scrambled to contain the deadliest outbreak of the virus outside China.

"Countries should be preparing for sustained community transmission,'' said Tedros Adhanom Ghebreyesus, leader of the World Health Organization. "Our message to all countries is: This is not a one-way street. We can push this virus back. Your actions now will determine the course of the outbreak in your country.''

Meanwhile, Japan said it would impose a 14-day quarantine on people arriving from China, South Korea.

Italy reported its national number of cases of the new virus had passed 3,000 on Wednesday.

Speaking at a press briefing from Rome, Italy's special commissioner for the coronavirus Angelo Borrelli said there had been a further 28 deaths to bring the toll to 107, the highest outside China.

Italy has seen its virus caseload explode since the first homegrown positive test was registered in northern Lombardy on February 19.

The Italian government announced the closure of all schools and universities across the country until March 15 as a measure to decrease and limit the contagion.

Summary of the key developments

WHO gave an update on the COVID-19 coronavirus outbreak on Tuesday afternoon

California declares state of emergency

Governor of California Gavin Newsom declared a state of emergency on Wednesday, as the first coronavirus-related death in California was reported.

There are currently 53 positive coronavirus cases in California.

What's the situation in Europe?

The EU raised its risk assessment of the outbreak, warning there is now a moderate to high risk of sustained transmission in member states and the UK in the coming weeks.

The warning comes amid a surge in cases in Europe and across the world. At an EU Commission press conference, the commissioner for health Stella Kyriakidou announced The European Centre for Disease Control and Prevention (ECDC) had raised the risk level, as the bloc tries to co-ordinate efforts to halt the spread of coronavirus.

"The risk of widespread sustained transmission of COVID-19 in EU/EEA and UK in the coming weeks is moderate to high, with more countries expected to report more cases and clusters," ECDC said on its website.

In Italy, the death toll stands at 107 and more than 3.000 infections - making it the worst-hit country outside of China.

Earlier in the day, Rome announced it is closing all its schools and universities for two weeks to contain the outbreak.

The rise in cases prompted travel restrictions against regions in the north, with the country linked to several new international cases.

The Italian government has announced that all sporting events in Italy will take place without fans present for at least the next month due to the virus outbreak.

Italy's Lombardy region, the epicentre of the European virus outbreak, is getting around its limited capacity to put patients in isolated intensive care units by using strap-on masks that provide continuous breathing assistance.

Lombardy's top health official, Giulio Gallera, says the masks, called CPAPs, which stand for continuous positive airway pressure, can be used in any hospital ward outfitted for respiratory assistance, freeing up ICU units for critical patients who really need them.

Lombardy has been hardest hit in Italy. Some 127 people are in intensive care in a region that currently can only provide 140 isolated ICUs for virus patients.

The strain on Lombardy's health system has forced authorities to seek to bring doctors out of retirement, accelerate graduation dates for nursing students, and incorporate doctors and hospital beds from the private sector to ease the strain on public hospitals.

France, which has the most cases after Italy, has urged citizens to stop shaking hands and banned events with more than 5,000 people.

The UK announced a huge surge in the numbers of those infected by the virus, up by 34 to 85.

Meanwhile, a civil servant in Brussels tested positive for COVID-19 coronavirus, becoming the first confirmed case within EU institutions. He works for the European Defence Agency in the Belgian capital and had just returned from a mission in Italy, a spokesman told AFP.

Hungary announced its first two cases of COVID-19. The two patients are students originally from Iran, who were asymptomatic.

The country has already suspended admitting asylum seekers into a pair of transit zones on the border with Serbia, where they file their asylum claims, because of the concerns about the outbreak.