A senior official at an international HIV/AIDS symposium in Beijing at the weekend said the government welcomes institutions from all over the world to do research in the country toward a vaccine.

Wang Yu, director of the Chinese Center for Disease Control and Prevention (China CDC), told the New Approaches to HIV Infection Management symposium that one potential vaccine has so far reached the human trials stage in China and one other is applying to proceed with them.

Though dozens of potential vaccines have been trialed in the past years, attendees said it could take another four to five years before they would know which might be developed into effective vaccines.

Robert Gallo, director of the US-based Institute of Human Virology and best known for his role in identifying HIV as the cause of AIDS, said problems involved in testing a vaccine included the virus' enormous variations and ability to mutate, and the way it integrates its genes into host cells' upon infection.

He called on all human virology institutions throughout the world to take on the task of developing possible HIV/AIDS vaccines.

The symposium was organized jointly by the France-based Fondation Mérieux, which aims to help prevent transmissible diseases worldwide, China CDC and National Institute of Health, and it began on Saturday and will run until tomorrow.

More than 150 domestic and overseas experts are attending it to discuss preventive measures against the virus, which now infects nearly 40 million people worldwide, including public education, provision of clean injecting equipment and methadone prescribing.

Hao Yang, vice director of the Health Ministry's Disease Control Department, told China Daily that by the end of the year 128 stations should have been established to provide free methadone to drug users to reduce transmission of HIV through sharing injecting equipment.

Meanwhile, people should be encouraged to take HIV tests, blood donors in particular, to prevent the spread of the virus through blood transfusions, said Gallo.

In China, at least 23 percent of total reported cases of HIV/AIDS involved infection from tainted blood in hospitals.

(China Daily December 5, 2005)