The latest case was infected from two British visitors who took Vietnam Airlines' London-Hanoi flight.

All new cases confirmed on March 11 are related to those who took international flights from or with stopovers in epidemic-hit countries.

Tightening immigration is part of efforts to curb the spread of the epidemic which has caused 45 coronavirus-infected cases in Vietnam.

Tracking down people who are linked with those positive with the virus remains one of measures to prevent contagion.

Four new cases today were found in Hanoi, putting the city at the top in Vietnam with 20 infected people.