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Coronavirus & the MHS Response | DOD HIV/AIDS Prevention Program | Research & Innovation | Coronavirus
The U.S. military has led HIV research since 1986, when it stood up the U.S. Military HIV Research Program at the Walter Reed Army Institute of Research at a time when reports of AIDS diagnoses showed almost twofold year-to-year increases in the United States.
Since then, MHRP has been at the forefront of the battle against HIV, helping to protect the U.S. military and improve global health through research to develop an HIV vaccine, reduce new infections, and advance strategies to induce long-term HIV remission.
In February 2020, the emergence of COVID-19 presented a new historic global public health challenge. Like HIV, it represented a destabilizing force that impacted the world, but existing HIV research data and lessons learned helped spearhead the development of COVID-19 vaccines at a “historic pace,” said U.S. Army Col. (Dr.) Julie Ake, director of the MHRP WRAIR, in Silver Spring, Maryland.
A Top Public Health Challenge Threatening Force Readiness
HIV is a “global destabilizing force impacting partner militaries and challenging public health in strategic geographies,” said Ake.
“HIV continues to threaten global health with 38 million people living with HIV worldwide and approximately 40 million deaths since 1981.”
And despite the development of prevention tools, there were 1.5 million new infections in 2020, as well as “several hundred new HIV infections in U.S. service members annually, which impairs military readiness, imposes a significant cost to military health systems, and threatens blood safety,” she added.
Military Advances in Medicine
Between 2003 and 2006, MHRP led the first-of-its-kind RV144 clinical trial, known as the Thai HIV Vaccine Study.
“It was the first clinical trial to show some efficacy in preventing HIV infection,” said Ake. “Study results showed that a preventive HIV vaccine is possible, and the landmark trial continues to provide scientific direction to help guide vaccine development and testing.”
She explained that the trial results, announced in 2009, paved the way for MHRP to conduct many experimental vaccine studies to help speed the discovery of a more effective vaccine.
“For example, we showed that longer intervals between the primary vaccination series and later doses boost improved immune responses,” she said.
The MHRP is now studying other ways to improve vaccine strength and breadth, she said, including:
- Novel vaccine platforms
- Fractional dosing, which involves using a fraction of the standard dose of a regular vaccine to reach more individuals or minimize the side effects of a full dose of vaccine
- Adjuvants, which are ingredients that can help people receiving a vaccine create a stronger immune response
“This year, we began a Phase 1 trial [which involves testing in humans] in Bangkok, Thailand to evaluate two HIV vaccine candidates,” said Ake. “One is administered with and another without the Army's novel ALFQ [a type of vaccine component called Army liposome formulation with a QS-21 adjuvant] to evaluate adjuvants and boosting strategies for better immune responses. We also began a trial at the WRAIR Clinical Trials Center in Silver Spring to select the optimal dose of the ALFQ adjuvant to use with protein-based vaccines.”
Additionally, Ake said MHRP began its first preclinical animal study of an mRNA HIV vaccine in early 2022. (Preclinical research occurs prior to clinical studies with humans, to find out if a drug or treatment is likely to be useful.)
“The WRAIR’s pilot bioproduction facility is developing the capacity to manufacture mRNA-based HIV vaccines for clinical trials on campus and internationally,” she said. “We think that this technology, along with improved adjuvants, are important for the next generation of HIV vaccine candidates.”
The study is ongoing and expected to wrap up animal activities in early 2023.
Why has an HIV Vaccine Taken so Long?
A vaccine that prevents HIV acquisition with “more than modest efficacy” has not yet been developed, said U.S. Air Force Col. (Dr.) Jessica Cowden, chief of the Department of Retrovirology at the Armed Forces Research Institute of Medical Sciences, in Bangkok, Thailand.
“Much of that is due to the extreme complexity of the virus, its mechanisms of infection, and its pathogenesis, or the process by which disease develops,” said Cowden. “Other factors are related to the global genetic diversity, the lack of animal models, and the changing landscape of prevention strategies which make large efficacy trials increasingly more difficult.”
The virus has many different HIV subtypes and strains circulating around the globe, added Ake.
“Once a person is infected, HIV continues to mutate rapidly. It hides from the immune system, making it very hard to target with a single vaccine,” she said. “The types of immune responses needed for protection are complex, and we continue to improve the strategies to induce these immune responses.”