The HIV pandemic – how much do we really need a vaccine?

A recent study published in the Proceedings of the National Academy of Sciences has developed a mathematical model to predict how the development of a HIV vaccine could impact the HIV pandemic we are currently facing worldwide. This model suggested that even a partially effective vaccine could dramatically reduce the number of infected individuals across the globe.

This research was supported by the National Institute of Health (MD, USA) and was carried out by researchers from the Oregon State University (OR, USA) and the Yale School of Public Health (CT, USA).

The model analyzed  HIV rates across 127 countries to determine the possible future of HIV control and prevention, and identified the most likely effective strategy moving forward.

It was estimated that if we were to carry on with the current levels of diagnosis and treatment, there would be approximately 49 million new HIV cases globally from 2015–2035.

“Both around the world and in the US, HIV and AIDS are still nowhere close to being under control,” stated Jan Medlock, who was the lead author of this study and is currently an Associate Professor at the University of Oregon.

“Given the efforts made against HIV/AIDS and the fact it can now be treated, the continued rate of spread is surprising. 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.”

The model developed in this study suggested that if the current targets for lowering HIV infection rates, set by the Joint United Nations Programme on HIV/AIDS (UNAIDS; Geneva, Switzerland) were achieved, 25 million of the expected 49 million new infections could be prevented.

Additionally, with the introduction of a 50%-efficacy vaccine by 2020, this model predicted the avoidance of a further 6.3 million infections worldwide.

However, as these predictions are based on a 95% success rate in diagnosis, treatment and viral suppression in every country, the researchers in this study suggested that these predictions “may be more aspirational than practical.”

This concern over the gap between reality and goals highlights the need to develop an effective new vaccine for use against HIV as soon as possible.

However, all in all, a combined effort to improve diagnosis and treatment, and the continued search for a more effective vaccine, is thought by scientists to be the most effective strategy moving forward against HIV.

The scientists of this study commented on their findings: “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.”

Source: Medlock J, Pandey A, Parpia AS, Tang A, Skrip LA, Galvani AP. Effectiveness of UNAIDS targets and HIV vaccination across 127 countries. Proc. Natl. Acad. Sci. USA.  doi: 10.1073/pnas.1620788114 (2017) (Epub ahead of print);


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