India, home to the world’s largest number of HIV infections after South Africa, is set to begin human trials of a new vaccine in January, a research institute said Tuesday.

The country has over 5.1 million people living with HIV/AIDS and experts say the number could quadruple by 2010.

Human trials of vaccines against different strains of the virus are already being conducted in the United States, Europe, Africa and South America. The Indian trial will focus on viral sub-type C, the most common in the country.

“It will be the first test in India of a HIV vaccine on humans,” said Ramesh Paranjape, a deputy director of the National AIDS Research Institute (NARI) based in Pune, around 100 miles south of Bombay.

In August the World Bank warned the disease would become the single largest cause of death in the world’s second most populous country unless there was a change in treatment policy and progress on prevention.

“A good, safe vaccine will help preventive efforts considerably so we are excited about beginning the trials,” Paranjape told Reuters.

India’s HIV problem has assumed serious proportions despite health programs to halt its spread. Over the years, HIV/AIDS has moved beyond traditionally high-risk groups such as homosexuals, commercial sex workers and drug users.

The virus is spreading into families, infecting mothers and children, and because of the widespread lack of awareness about the illness, many people do not even know they are infected.

Experts say the most alarming trend is the spread of the disease to villages, with rural India accounting for 59 percent of infections compared with 41 percent in cities.

The first phase of testing of the vaccine, the adeno-associated virus-based HIV sub-type C, will be conducted with about 30 adult volunteers, Paranjape said.

The NARI scientists will monitor the volunteers over a period of one year to test for side effects and the immune system’s response to the vaccine.

“It is a very significant step,” said Anjali Nayyar, country director of the International AIDS Vaccine Initiative, a private non-profit organization that is providing technical support for the trials. “A vaccine is important for the Indian population as the country needs low-cost intervention to fight AIDS.”