The three men, aged 37, 38 and 41 and numbered patients 1064, 1065 and 1066, are from the north-central province of Quang Binh, the Central Highlands province of Dak Lak and the south-central province of Binh Dinh.
They’d been quarantined on arrival upon landing September 2 at Hanoi’s Noi Bai Airport on a direct flight from Uzbekistan.
The three men tested positive for the virus on September 15-16 and are being treated at the National Hospital for Tropical Diseases in Hanoi.
Thursday also saw four Covid-19 recoveries of patients aged 29-62 in Hanoi and Da Nang City.
Vietnam has recorded 1,066 Covid-19 cases so far, with 35 deaths. Many of the deaths have been of elderly patients with underlying conditions like kidney failure, cancer and diabetes.
Over 30,000 are quarantined nationwide at present.
The country has recorded no community transmission of the novel coronavirus in two weeks.