78 new cases were recorded in Bac Giang Province, 21 in Bac Ninh Province, six in Dien Bien Province, two in Da Nang City, and one each in HCMC and Hanoi.
The cases in Bac Giang have all made contact with coronavirus cases associated with the province's Quang Chau and Van Trung industrial parks which have been shut down as major coronavirus hotspots.
Most of other cases have all had contact with coronavirus cases or detected inside existing quarantine zones.
Only one case in Da Nang City remains unclear of contagion sources. This is a 31-year-old woman in Son Tra District. Health authorities are tracing her contact history.
Vietnam recorded a total of 175 domestic cases Wednesday, taking the total such cases since April 27 to 1,648 in 28 localities.
Bac Giang leads with 605 cases, Bac Ninh 353 and Hanoi 257 (in which 118 are in two locked down hospitals).
The national tally is now at 3,217. Over 121,000 people are being isolated and monitored.