Vietnam's Ministry of Health confirmed a total of 509 cases of Covid-19. However, 369 of the affected patients have recovered and been discharged from hospitals.
The latest 45 cases were all linked to hospitals in Danang.
The Vietnam government has started mass coronavirus testing in the capital Hanoi, locked down tourist spots, banned gatherings in its economic hub and urged tens of thousands of domestic travellers to report to authorities on Thursday, as the country scrambled to contain the new spread of the virus.
The ministry overnight sent a special task force of health experts, along with more than 1000 health workers, to Danang to help handle the deteriorating situation there, it said.
Vietnam had until Friday been the only nation with a large population not to have suffered fatalities from the coronavirus pandemic.
It reported its first case in late January.