YSPH Model Sheds Light on How Millions of HIV Cases Can Potentially Be Averted

Over the past few years, several advancements have been made in the fight against HIV. Thanks to antiretroviral therapy, HIV-positive individuals are able live as long as those who are uninfected. Still, a staggering 36.7 million individuals around the world are living with the infection, and new cases are reported each day. Many researchers have channeled their efforts into attempts to develop effective HIV vaccines, but the impact of these vaccines remain unknown, perhaps until now.

Researchers from Yale School of Public Health have developed a mathematical model that has predicted that using vaccines in tandem with other interventions could possibly prevent millions of HIV cases in the upcoming years.

The research team analyzed data obtained from 127 countries to “determine how United Nations goals for diagnosing and treating HIV, as well as vaccination, would impact the number of future cases.” Their findings are featured in a paper published in Proceedings of the National Academy of Sciences; Anthony Fauci, MD, head of the National Institute of Allergy and Infectious Disease edited the research paper.

The mathematical model and the research paper are the result of a collaborative effort headed by Alison Galvani, PhD, Burnett and Stender Families professor of Epidemiology (Microbial Diseases), at the School of Public Health’s Center for Infectious Disease Modeling and Analysis (CIDMA). One of CIDMA’s chief goals is “to use interdisciplinary mathematical modeling approaches to quantify the impact and cost-effectiveness of vaccines for a range of infectious diseases.”

To make headway in the ongoing fight against HIV, quantifying the impact of new interventions is important. In order do this, a mathematical model was born, one that considered the “progression, transmission, and intervention” of HIV. The researchers found that “maintaining the status quo of treatment and diagnosis would lead to an estimated 49 million new cases of HIV/AIDS globally between 2015 and 2035.” However, after factoring in the possibility of an effective HIV vaccine, 17 million of those cases could potentially be averted.

Although vaccination would be a key player in cutting down on the number of infections, one of the biggest challenges in the fight against HIV remains the “relatively low rate of testing and diagnosis.” Many are familiar with the ambitious “90-90-90” global treatment target set by the Joint United Nations Program on HIV/AIDS (UNAIDS). The goal calls for 90% of individuals to receive diagnosis, that 90% of infected individuals receive antiretroviral treatment, and 90% of those who are being treated achieve viral suppression—all by the year 2020. By 2030, the goal is for 95% of all three targets be achieved in each country.

According to the press release, “Under status quo interventions, a median of 49 million new infections globally was projected over the next 20 years.” It had been predicted that the 90-90-90 goal could prevent 25 million of these estimated infections, with the introduction of “a partially efficacy vaccine” cutting back on an additional 6.3 million cases.

“Even if the ambitious UNAIDS goal regarding treatment as prevention are achieved, the additional benefit of a partially efficacious HIV vaccine would be enormous in terms of turning the tide on the pandemic and saving millions of lives across the globe,” Dr. Galvani explained in a press release.

This study has provided researchers with answers pertaining to the impact of vaccination, and this information can be used to inform better HIV-related policies on national, as well as international, levels. Furthermore, the research paper also provides information pertaining to “regional and country-level projections of the impact of HIV vaccine and interventions,” which is imperative when it comes to crafting certain strategies to address “region-specific concerns” as well as any complications that can result from treatment.

In the press release, Dr. Galvani mentions a particularly promising trial that is being launched to test the efficacy of a new HIV vaccine in South Africa, a place that has been hit especially hard by the virus. She said, “Given improvements on a former partial efficacy vaccine, I’m hopeful that this new vaccine will prove sufficiently efficacious to be licensed.” She concluded, “Our results show that even a 50% efficacy vaccine would be highly impactful.”