"The dengue outbreak shows no sign of easing up, and could worsen," director of the city Department of Health, Tang Chi Thuong, said Monday.
The number of severe cases this year is several times higher than last year, and the situation in the final quarter of the year is likely to remain "dire," he said.
This year there have been around 60,000 cases, several times the number the city suffered in previous years.
In recent months there have been over 100 dengue fever hotspots every week, Thuong said.
Luong Chan Quang, a doctor at the Pasteur Institute, said HCMC has accounted for 80% of all cases in the country this year, and the outbreaks are likely to persist due to the warm and humid weather in which mosquitoes thrive.
Vietnam has been trying to find an effective way to tackle dengue, one of the biggest killers of the 28 common infectious diseases it is plagued by.
The only vaccine for it available globally is not recommended for people who have not had dengue before.
The World Health Organization (WHO) said in January the incidence of dengue has grown dramatically around the world in recent decades and that a vast majority of cases are asymptomatic or mild and self-managed, and hence, the actual numbers of dengue cases are under-reported.
The number of dengue cases reported to WHO increased from 505,430 in 2000 to 5.2 million in 2019.
The number of deaths increased from 960 to 4,032, with mostly younger people being victims, it said.