Five of the cases are linked to a migrant worker (patient 2899) who returned from Japan and tested positive in the northern province of Ha Nam after completing his mandated two-week quarantine in Da Nang.

Four of these patients – numbered 2901, 2903, 2908 and 2909 – father, mother, wife and child of the migrant worker, while patient 2910, also from Ha Nam, tested positive in HCMC, where he is visiting relatives.

The migrant worker had returned from Japan on April 7 and been quarantined at the Alisia Beach hotel in Da Nang. He tested negative for the coronavirus thrice during his stay. On April 22 he returned home to Ha Nam and self-isolated himself. But, on April 24, he was taken to a local medical facility for testing after he developed symptoms of cough, fever and throat pain.

Patient 2910, meanwhile, had shared a meal and drink with the Japan returnee in Ha Nam before boarding Vietjet Air flight VJ133 on April 27 from Hanoi's Noi Bai International Airport to HCMC's Tan Son Nhat International Airport. From the airport, he took a taxi to his relatives' house in Binh Tan District.

After he heard that the Japan returnee had tested positive for the novel coronavirus, he reported to the medical station in Binh Hung Hoa Ward in Binh Tan and made a health declaration.

HCMC is now conducting contact tracing for Patient 2910. It has asked passengers and crew of flight VJ133 on April 27 to report to medical facilities.

Vietnam’s Covid-19 tally of 2910 cases includes 2,516 recoveries and 35 deaths.