Hanoi led in the number of new cases at 2,705, followed by Da Nang City with 783 cases and Hai Phong with 496 cases.
In the past 24 hours, 109 Covid-19 patients have died, including 20 in Hanoi.
Vietnam has recorded 185 cases with the Omicron variant to date, with 92 of them in HCMC.
Since the pandemic started last year, the death toll in Vietnam has climbed to 37,780, or 1.67 percent of all infections.
In the latest wave that hit the country in late April, more than 2.26 million cases have been confirmed and 2.06 million of them have recovered.
So far, 76.9 percent of the population have been vaccinated with two doses.