Of the new cases, five each were recorded in the northern Bac Giang Province and the southern Tay Ninh Province, two in Mekong Delta's Long An Province, and one in northern Thai Binh Province.

The cases in Bac Giang are all associated with outbreaks in local quarantined zones and industrial parks.

For the cases in Tay Ninh, their sources of transmission are under investigation.

In Long An, one case had made contact with a confirmed coronavirus patient and the other has unclear source of transmission.

In Thai Binh, one case is a woman coming into contact with a Covid-19 patient.

Aside from those 13 patients, HCMC on Friday night had registered with the Health Ministry for the tag numbers for 563 new patients.

They are among 667 cases it had detected over a 24-hour period as of Friday morning: 14 of were detected through coronavirus screening in hospitals, one was exposed to the virus while working as a nurse at the Binh Thanh District medical center, another was detected through expanded Covid-19 testing, two tested positive in centralized quarantine zones, 10 cases are being contact traced and two were imported.

The other 637 cases were detected within quarantine zones and other locked-down areas, Nguyen Tan Binh, director of the HCMC Department of Health, said Friday.

Almost two months into the new Covid wave, the fourth one and the most challenging one Vietnam has faced yet, the nation has officially confirmed 11,794 domestic cases in 47 of its 63 cities and provinces.

Bac Giang Province accounts for most infections, with 5,554, followed by HCMC with 2,960.