The best hopes for turning a corner on HIV and AIDS, according to a new analysis, is the development and widespread use of a vaccine that's partially effective against HIV, along with more progress toward diagnosis and treatment.

The analysis, published Monday in Proceedings of the National Academy of Sciences, addresses the reality that even though HIV and AIDS can now be effectively treated in most cases, actual control of the global epidemic is elusive.

In trying to look into the possible future of HIV/AIDS, and what steps might best help address the issue, researchers from Oregon State University (OSU) and the Yale School of Public Health, in work supported by the US National Institutes of Health (NIH), have developed a model of HIV progression, transmission and intervention tailored to 127 countries around the world.

Data in the analysis show that HIV infections are surging, with millions of people who have been diagnosed not getting treatment. Since 2010, the global prevalence of HIV infections has increased to 37 million individuals; and in 2014, 1.2 million people in the US were infected. 87 percent of those infections have been diagnosed, but only 52 percent of people known to have HIV in the US are being treated.

"Both around the world and in the US, HIV and AIDS are still nowhere close to being under control," Jan Medlock, an associate professor and mathematical epidemiologist in the OSU College of Veterinary Medicine, and lead author on the analysis, was quoted as saying in a news release from OSU. "Given the efforts made against HIV/AIDS and the fact it can now be treated, the continued rate of spread is surprising," he noted. "Even the cost of drugs, at least for the initial treatments, is relatively low. But this problem is still getting worse, not better, and our research suggests the value of prospective vaccines could be very significant."

Under the "status quo" levels of intervention, the research found, the world may expect about 49 million new cases of HIV infection during the next 20 years. Since the first report of AIDS in 1981, about 75 million people have been infected with HIV and 36 million deaths have been attributed to AIDS. If ambitious targets for diagnosis, treatment and viral suppression are reached, 25 million of these new infections could be prevented, the study concluded. Adding a vaccine by 2020 that was even 50 percent effective could prevent another 6.3 million infections, and might have the potential to reverse the HIV pandemic.

The latest United Nations targets, established in 2014, are "95-95-95", meaning a 95 percent success rate, by country, in diagnosing HIV infections; treating those infected; and achieving viral suppression in those being treated. 

Vaccines already exist, but are mostly in clinical trials. One candidate has about 60 percent efficacy for the first year after vaccination, dropping to 31 percent efficacy 3.5 years later. A modified version of this vaccine began large-scale, phase three trials last November in South Africa, with hopes for higher efficacy.

A combined approach of better diagnosis, treatment and a vaccine is the best bet, the report concluded. "Given the challenges inherent in treatment as prevention and in vaccination, a combined approach would be the most feasible and effective strategy to address the HIV pandemic in each of the 127 countries considered."