28 cases were recorded in Bac Giang, four in Hai Duong and one in Da Nang.
The cases in Bac Giang are associated with existing outbreaks at the province's Quang Chau, Van Trung and Dinh Tram industrial parks.
All the cases in Hai Duong had made contact with confirmed coronavirus cases.
The case in Da Nang is associated with a local bar which has been deemed as a coronavirus hotspot.
With the new patients added, Vietnam has recorded 2,254 local Covid-19 cases in 30 cities and provinces since the new wave started on April 27.
Among the infected localities, six provinces have gone 14 days without any new cases. They are Yen Bai and Quang Ninh in the north, Quang Ngai, Quang Nam and Nghe An in the central region and Dong Nai in the south.
Bac Giang has continued to have the highest infections so far, with 980 cases, followed by its neighbor Bac Ninh with 474.