The Cho Ray Hospital announced on Friday night that 12 of its patients have been infected with the influenza virus A/H1N1 so far.
This makes it the second swine flu hotspot in the city after the Tu Du obstetrics hospital.
The virus was detected in the Nephrology Department of the hospital after five kidney patients were tested positive for the A/H1N1 type influenza on June 11.
Professor Nguyen Truong Son, director of the hospital, said it as the first-ever swine flu outbreak at Cho Ray, one of the country’s oldest hospitals.
He said the hospital was working with the Pasteur Institute in the city to deploy measures to monitor and prevent the epidemic from spreading.
All infected patients have been quarantined for treatment and the hospital immediately isolated the Nephrology Department for disinfection, Son said.
A medical staff of the hospital with symptoms similar to that of the viral infection has been asked to stay home for observation.
On May 30, a 26-year-old woman in Saigon who had tested positive for influenza virus A/H1N1 died after she attempted self-treatment at home for five days, making her the first swine flu casualty reported in the country for about two years.
The hospital subsequently quarantined more than 80 patients and staff members that it deemed at risk and isolated the Laparoscopy Department for three days for disinfection. The situation is said to be under control now.
Pregnant women and infants and young children under two are among the groups identified by the World Health Organization as being at increased risk for complications arising from swine flu.
The H1N1 virus broke out worldwide in 2009 and was responsible for more than 17,000 deaths.
Some strains of the virus are endemic in humans and cause a small fraction of all seasonal flu while others are endemic in pigs and birds, better known as swine flu and avian flu.
Vietnam has recorded more than 11,000 human infections so far, including first deaths in April 2013.