Almost 30 years after its discovery, the incurable AIDS virus continues to destroy lives around the globe. However, a new analysis of a 2009 AIDS vaccine trial has brought scientists one step closer to finding a preventive.

Researchers reported April 5 in the New England Journal of Medicine that the partial success of a Thailand-based trial that protected 31 percent of participants from infection may have been due to varying levels of antibody resistance in the patients.

“These studies provide new insights that may lead to a better and longer-lasting HIV vaccine,” said lead author Dr. Jerome Kim, deputy director for science of the U.S. Military HIV Research Program, in a press release earlier this month. “They may also help scientists prioritize vaccine candidates for future clinical trials, which would accelerate the development of a vaccine.”

In the trial, researchers studied 16,402 HIV-negative volunteers between 18–30 years old, the average ages of infection.

Col. Nelson Michael, another vaccine researcher, explained that different types of antibody responses in the body determine who gets infected and who does not.

In this case, study authors suspect that an antibody called IgG might have linked itself to the surface of the HIV protein V1V2, which helped prevent infection in some people.

Patients whose blood contained high levels of a different antibody called IgA appeared to have less protection against HIV than their IgG-loaded counterparts, leading scientists to believe that these antibodies could play a critical role in developing an effective vaccine.

Michael said although the results are promising, the 31 percent prevention rate seen in the 2009 trial was not large enough to have a public health impact. He said he sees it as a “good and promising start.”

Though considered promising by many, some health officials are skeptical that an HIV vaccine could make a difference in Third World countries because of the frequent use of unclean needles in these regions.

Dr. Susan Lowe, a general practice physician at the Caribbean Association of Medical Councils in Jamaica who reviewed the analysis, contracted HIV in Jamaica after she was injected with an infected needle.

“[A]fter my experience, I would rather take my chances with no vaccine unless serious changes are made to how testing and use is regulated,” Lowe said.

According to the Centers for Disease Control and Prevention website, there are an estimated 1.8 million people ages 13 and older in the U.S. living with HIV, 20 percent of whom had undiagnosed infections.

In 2010, the World Health Organization reported that there are an estimated 34 million people worldwide who are HIV-positive.

This news makes Bob, 47, an HIV-positive photographer from New York City, hopeful that a vaccine is around the corner, although he thinks researchers have a long way to go before that goal is reached. To protect his identity, Bob asked The Chronicle not to print his last name.

“From what I’ve read, I would be skeptical if it were released today,” Bob said. “But it does give hope that they’re working towards finding [a vaccine], and this seems more promising than anything else they’ve tried.”

Although he considers himself fortunate because he has not experienced AIDS-related symptoms since being diagnosed with HIV in 2000, Bob said the stigma of having HIV and the expensive medications he must take on a daily basis have made life more difficult. He hopes a vaccine will be developed so people can avoid infection in the future.

“I think it could be absolutely amazing for people not only in the U.S. but around the world because so many people in other countries are dying,” he said.