The southern metropolis registered 26 new patients, the northern Bac Ninh Province 23 and its neighbor Bac Giang 16 while the central Ha Tinh Province reported one.

Of the cases in HCMC, eight are related to a hotspot that was detected late last month from a Christian congregation in Go Vap District, five have had contact with Covid-19 patients and for the remaining 13, the authorities are looking into their sources of transmission.

In Bac Ninh, 18 are linked to clusters at its two industrial parks of Que Vo and Khac Ninh, two are related to another cluster in Dai Phuc Ward of its capital Bac Ninh Town, one had contact with a previously confirmed patient, and health officials are tracking down the route of transmission for the remaining two.

All cases in Bac Giang were recorded in centralized quarantine camps and areas under isolation, and they are all related to clusters at its industrial parks.

The case in Ha Tinh is a 45-year-old man in Hong Linh Town whose source of infection is still unclear.

Vietnam has recorded infections in 39 cities and provinces so far in this new wave of Covid-19, which started on April 27 and has been the nation's most challenging outbreak yet.

Bac Giang and Bac Ninh account for most patients, at 3,621 and 1,205, followed by HCMC with 527 and Hanoi with 447, including 95 in a locked down hospital.