35 cases were recorded in the northern province of Bac Giang, 12 in its neighbor Bac Ninh and one in the central city of Da Nang.
All the cases in Bac Giang and Bac Ninh are associated with outbreaks in the provinces' industrial parks and have been quarantined prior to test results.
The case in Da Nang, a 72-year-old woman, had made contact with a confirmed coronavirus patient.
Five weeks into the new wave, Vietnam has recorded as many as 4,597 local infections in 37 of its 63 cities and provinces.
Bac Giang and Bac Ninh, home to major foreign manufacturing plants, are having the highest numbers of infection, at 2,459 and 891.