NEW DELHI: As many as 150 passengers with symptoms of coronavirus have so far been referred to isolation facilities in the country as the government steps up efforts to deal with the outbreak.Making a suo motu statement in the Rajya Sabha on Friday, health minister Harsh Vardhan said existing visas are no longer valid for any foreign national travelling from China."People travelling to China henceforth will be quarantined on return," he said.Screening of passengers has been initiated since January 18 and this facility has now been extended to 21 airports, Vardhan said, adding that universal thermal screening has been made mandatory for all flights coming from Singapore and Hong Kong as well.He said three people in Kerala have tested positive for coronavirus so far.A group of ministers (GoM), headed by the Union health minister, has been constituted to monitor the situation. This group consists of ministers of external affairs , home, shipping and civil aviation.Vardhan said 1,275 flights have been screened for coronavirus so far, covering 1,39,539 passengers.As many as 150 passengers with symptoms of the infection have been referred to isolation facilities, he added.Screening has also been initiated at all integrated check posts on the Nepal border after a confirmed case was reported in Nepal.The three people who tested positive for coronavirus had travel history to Wuhan in China but are now reported to be clinically stable, the health minister said.