BEIJING (AP) — China is encouraging tens of millions of migrant workers not to travel home during February’s Lunar New Year holiday to prevent further spread of the coronavirus.

The measure from the National Health Commission is not a direct travel ban but is still extraordinary because Lunar New Year is China’s most important traditional holiday and the only time of the year when many workers have the opportunity to travel home to see their families.

The NHC said it was encouraging provincial governments to persuade workers to follow the suggestion while taking into account their personal wishes. It also said workers who stay behind should be paid overtime and offered other opportunities to take vacation.

China has all but eradicated local transmission of the coronavirus, but authorities remain on high alert over a possible resurgence. Already, schools are scheduled to begin the Lunar New Year vacation a week early and tourists have been told not to visit Beijing, the capital, during the holiday.