The 31-year-old's family had been unable to return to London after a stint in Brazil due to the outbreak, so the forward has been allowed to return to his home country by the Blues.
The ex-Shakhtar Donetsk winger is back with his wife and children, with the consent of his Stamford Bridge bosses, and will remain there indefinitely while Europe and the world try to get to grips with the spread of the virus.
His long-term future of Willian remains up in the air as he is due to fall out of contract and as yet there is no sign of him penning a new one, as a host of clubs show an interest in him.
The enforced break should at least give Willian plenty of thinking time regards his next move, while the same can be said of Chelsea.
#Boss Frank Lampard has decisions to make on a number of players and is likely to be mulling them over during this time.
Willian is a player he wants to keep, but there is still work to be done on the deal.
The Premier League will be suspended until April 30 at the earliest, with all clubs shut down and top stars training at home.
Meanwhile, Chelsea's England forward Callum Hudson-Odoi is recovering well after testing positive for coronavirus earlier in the month, with the Blues confirming his progress back towards full health on Monday.
"We are pleased to report Callum Hudson-Odoi is now feeling fine and back to his usual self following the period of self-isolation required after the player tested positive for COVID-19," read a statement on Chelsea's website.
"In addition to feeling good, the young winger is hard at work training at home to build and maintain his fitness, as are the rest of the Chelsea squad."