Updated: Tuesday, Jan. 31, 2023, at 11:31 p.m.

The School of Medicine and Health Sciences achieved a 97 percent success rate after conducting human trials of an HIV vaccine over the past year, according to a release the school issued last month.

David Diemert, the clinical director of the GW Vaccine Research Unit, said the vaccine achieved a desirable immune response in 97 percent of the participants and no participants experienced concerning health or side effects from the vaccine. He said the vaccine “stimulated” certain immune system cells to start making broadly neutralizing antibodies, bnAbs, that are successful in blocking a wide variety of HIV variants and strains. 

“This was a significant breakthrough, which is one reason that it was published in Science and has been receiving a lot of press,” Diemert said in an email. “There is a lot of excitement that this trial showed that designing a strategy to produce bNAbs to protect HIV-negative individuals is really achievable.”

Diemert, a professor of medicine in the School of Medicine and Health Sciences, said a finalized vaccine available for general use is still “several years” away and the final product could be a sequence of two or three different vaccines administered to an individual over several months. He said each vaccine will “push” the individual’s immune system to make bnAbs.

“Each vaccine will push the immune system in a specific direction towards making bNAbs,” Diemert said in the email. “The study that was just published is the first step in this process, and is proof of concept that this strategy could work.”

He said the results show it’s possible to target germline B cells — cells found in the lymph nodes —  to start the process of producing bnAbs. Diemert said the “significant breakthrough” of the concept led to the results to be published in Science. 

Diemert said the next steps of the trials are already underway with the second Phase 1 trial of an mRNA vaccine. He said the mRNA vaccine “encodes” for the same protein tested in the trials that had the results published last month.

He said previous vaccines that were proven to be unsuccessful were based on one or a few strains, while HIV has multiple variants and strains that each require attention. Diemert said this vaccine is the first HIV vaccine tested in humans that produces broadly neutralizing antibodies that are successful in stopping a variety of HIV strains and variants. 

“What this means for people at risk for HIV is that this work may eventually lead to the development and approval of a vaccine strategy that could prevent people from getting infected if they’re exposed to the virus,” Diemert said.

The United States Department of Health and Human Services started developing a vaccine for HIV in 1984 and began the first clinical trial in 1987, according to the National Institute of Allergy and Infectious Diseases. Since 1987, multiple vaccine trials have started but have been later halted due to safety concerns or a lack of efficacy in treating and preventing HIV.

The U.S. Army sponsored the RV144 vaccine trials in 2009, which developed a vaccine for two dominant HIV strains in Thailand. The vaccine lowered the rate of HIV infection by 31 percent, but the trials were stopped in February 2020 with the efficacy rate dipping to 31 percent, according to the U.S. Military HIV Research Program.

HIV is transmitted through anal and vaginal sex, pregnancy, birth, breastfeeding and sharing needles, syringes and other drug injection equipment, according to the CDC. HIV weakens a person’s immune system by destroying cells that fight disease and infection. The number of patients with AIDS – one of the forms of HIV – shot up from 20,000 cases worldwide in 1985 to 400,000 globally in 1988 in one of the most severe HIV epidemics in recent history.

More than 300,000 people in the U.S. were diagnosed with HIV in 2020. Sub-Saharan Africa contains two-thirds of all HIV cases worldwide, according to the Kaiser Family Foundation, a nonprofit organization focused on nationwide and global health issues.

The International AIDS Vaccine Initiative selected GW as one of two trial sites for the HIV vaccine in October 2018, and GW researchers distributed the first dose last January. The trial’s participants received either two placebo, two low-dose or two high-dose vaccines eight weeks apart, and researchers analyzed the results after collecting cells from the blood and lymph nodes of participants.

Individuals with HIV can take medication known as antiretroviral drugs that lower the viral load of HIV by 81 percent in the Americas and by 94 percent in Africa, according to the World Health Organization.

Experts in HIV research said the trial’s success rate delivers encouraging signs for HIV treatment as countries continue to remain without vaccination options for treatment.

Andrea Kovacs – a professor of pediatrics, pathology and population and public health sciences at the University of Southern California – said the vaccine’s antibodies, proteins that neutralize HIV strains, are necessary for preventing mutations and transmission.

The U.S. made more than $21 billion available for the AIDS response in low-income countries and about 60 percent of the funding came from domestic sources in 2021, according to UNAIDS.

“The first priority will be for prevention of transmission between sexual partners or even mother-to-child transmission,” Kovacs said.

Kovacs said medical professionals should prioritize vaccinating populations at high risk for HIV, including men who have sex with men in the United States and young girls in sub-Saharan Africa, who account for the highest percentage of newly diagnosed HIV cases overall. She said the strategy of combining multiple prevention methods, like vaccinations and medication, will be crucial to reduce transmission, especially internationally.

Richard Wamai – an associate professor of culture, societies and global studies at Northeastern University – said access to HIV vaccination and treatment is “critical” in preventing infection and death, but access is “complicated” in the United States because of health insurance issues, racial discrimination and other forms of inequality that manifest in health disparities.

Wamai said he traveled to eastern Africa to study biomedical HIV intervention in December 2022, where the number of new infections is higher as part of the “HIV belt.” He said structural intervention, like increasing access to sex education for girls, and behavioral intervention, like distributing condoms, are necessary in combination with biomedical interventions, like the vaccine.

“HIV, it doesn’t have to be a killer,” Wamai said. “Well, we still have 600,000 persons who died of HIV globally in 2021. We can prevent these deaths because there is good treatment that is available.”

This post has been updated to correct the following:
This post has been corrected to remove an incorrect reference to mRNA. The story was also corrected to include Diemert’s comment and summary of the vaccine trials. We regret these errors.