The northern province of Hai Duong recorded 14 new cases, nine of them factory workers in Chi Linh Town, which has been locked down.
The northern province of Quang Ninh has confirmed four new patients and the remaining case is in the Central Highlands province of Gia Lai.
Meanwhile, the central province of Quang Nam has confirmed one imported case, that of "Patient 1902," a 25-year-old man who landed Monday at the Da Nang International Airport on Vietjet flight VJ5925 from Japan.
Vietnam has recorded 329 community transmissions of Covid-19 in 10 localities since January 28. Hai Duong leads with 240 cases, followed by Quang Ninh 42, and Hanoi 21.
The national tally is now at 1,911, with 1,461 recoveries and 35 deaths. Most active patients are in stable conditions with 12 having tested negative for the novel coronavirus at least once.
Over 48,000 people are in quarantined with over 22,000 in quarantine facilities, 378 in hospitals and the rest at home or other designated accommodations.
Globally, Covid-19 has claimed 2.2 million lives among 104 million confirmed cases.