The second leg between Valencia and Atalanta was one of several fixtures under review in Spain. The opening match between Sevilla and Roma in the Europa League round of 16, which is scheduled to take place two days later, could face a similar fate. Madrid-based outfit Getafe will host Inter Milan on March 19.
Spain's health minister, Salvador Illa, recommended the measures amid growing concerns about the new coronavirus. The country has reported more than 200 cases of COVID-19 and three deaths since the outbreak began.
A group of Valencia fans asked authorities to keep the Mestalla Stadium open to season-ticket holders, according to Joseph Wilson of The Associated Press, but UEFA declined.
The situation is far worse in Italy, where more than 100 people have died from COVID-19 and more than 3,000 people have been infected. The majority of the cases have been reported in the province of Lombardy. Atalanta are from Bergamo, which is a small city inside the region.
Four Valencia fans who traveled to watch the first leg in Milan - where Atalanta have played their Champions League matches this season - were tested for COVID-19 shortly after returning home, according to Spanish newspaper AS. The regional government ordered those people to self-isolate as a precaution.
Atalanta currently hold a 4-1 lead over Valencia on aggregate in the round of 16.