The head of the Department of Preventive Medicine and Environment, Nguyen Huy Nga announced three more cases of the A/H1N1 flu virus on June 22.

A medical worker checks a suspect of the flu at the National Institute of Infectious and Tropical Diseases(Photo; VNA)

With three more people infected with swine flu, Vietnam now has 52 confirmed cases.

Twenty have recovered and been discharged from hospital. The remaining patients are in stable conditions, with no reports of deaths. 

Seven contracted the disease from infected relatives returning from overseas, and

Receiving news that some Brazilian and Japanese scientists believe the virus is presenting signs of mutating, Dr. Nguyen Tran Hien, director of the Central Institute of Hygiene Epidemiology, said that World Health Organization (WHO) has issued a warning but no official announcement of a mutation of the A/H1N1 virus has been made.

The Institute of Hygiene Epidemiology is working closely with the Center for Disease Control and Prevention to study the virus’ make-up and transmission.

In related news, a 49-year-old woman infected with A/H1N1 virus died in the Philippines last week, the country's first related fatality, its government announced.

China's first batch of A/H1N1 flu vaccines were announced by a pharmaceutical firm Monday.

The vaccines are expected to hit the market in September after safety tests and clinical tests, said Hualan Biological Engineering.

In order to create vaccines, eleven pharmaceutical companies received the virus from the WHO on June 3.

As of June 22, 44,287 cases of A/H1N1 flu, including 231 deaths, have been reported in 100 countries and territories around the world, said the World Health Organization.