The new patients were recorded in Hanoi, and Bac Giang, Bac Ninh and Lang Son provinces, all linked to previously confirmed patients.
Bac Giang reported 10 cases relating to COVID-19 patients confirmed at the Van Trung Industrial Park in Viet Yen district.
Bac Ninh registered six cases linked to previously confirmed patients at the cluster in Thuan Thanh district.
Hanoi got five cases, including one linked to a group of Chinese experts who flouted their self quarantine protocols in Vietnam last month, and another linked to the director of a state-owned construction firm who allegedly failed to declare his travel history to coronavirus hotspot Da Nang.
The city's National Hospital for Tropical Diseases recorded one case and the K Hospital that treats cancer in the capital three. Both hospitals have been locked down since last week.
Lang Son recorded four cases related to previous infections.
The latest cases brought the national tally to 3,740. More than 2,600 patients have fully recovered and 35 have died.
Vietnam's new COVID-19 wave has seen 713 local cases recorded in 26 cities and provinces since April 27.