Will the Moderna HIV Vaccine Trials Succeed?

On August 11, Moderna, the biotech company behind one of the COVID-19 vaccines, posted a study record announcing that they were set to start Phase 1 of human trials on a HIV mRNA vaccine. These trials will consist of 56 adults between the ages of 18 to 50 years old who don't have HIV and test for safety, immune responses and antibodies.

Health experts weighed in on the likelihood of the Moderna trials succeeding and the ways in which public health institutions would have to transform to be prepared for a vaccine.

With mRNA technology, Pfizer and Moderna developed COVID-19 vaccines in record time. mRNA vaccines work by sending instructions to the body's cells to express proteins which induce an immune response that triggers the creation of antibodies. While in the case of COVID-19 it has been successful, this game-changing technology may not work so well with a trickier virus like HIV that mutates much more quickly and evades the body's immune system.

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Dr. Otto Yang, a professor of infectious diseases at the David Geffen School of Medicine at UCLA, speculated that the likelihood of the Moderna trials succeeding were "very low." He explained that for the most part, successful vaccines mimic the natural immunity which can happen if a person is infected with a virus. Dr. Yang used the example of smallpox. Though smallpox had a fatality rate of 30%, the other 70% which survived are considered to have had life-long protection. With COVID-19, most people who get it recover and gain antibodies (though it's still unknown for how long they will protect you). Since in the vast majority of cases the body's immune system doesn't fend off HIV, a successful vaccine will have to do something that doesn't naturally occur.

"I'm not fully privy to the Moderna vaccine design, but as far as I know they're not doing anything other than putting in genes for HIV proteins," Dr. Yang said. "If they do that, basically it is a mimic of natural infection. If you copy a failing process, you're probably going to get failure."

Dr. Rona Vail, Clinical Director of HIV Services at Callen-Lorde, explained how creating a vaccine for HIV is vastly different from making one to fend off COVID-19.

"We are a very long way from an effective HIV vaccine. There's hope that we're getting closer to knowing what an effective HIV vaccine might look like and that's what I think this technology does, which is exciting." –Dr. Rona Vail

"HIV is much better at hiding its surface proteins, so it's easier to get inside the cells," she said. "Within 72 hours of infection, HIV has incorporated itself into our genetic material. In order to try to fight this virus, we have to find ways to develop a very broad spectrum of antibodies very quickly at the moment somebody is infected because we have a very short time frame before it's actually just part of our genetic system."

Dr. Vail argues that mRNA technology's flexibility offers the possibility of getting rare immune B cells to create broadly neutralizing antibodies that, unlike regular antibodies, target "more hidden" parts of the virus that aren't "as variable."

She added, "We are a very long way from an effective HIV vaccine. There's hope that we're getting closer to knowing what an effective HIV vaccine might look like and that's what I think this technology does, which is exciting."

Moderna's Phase 1 trials are set to end in the spring of 2023. Even if in the most optimistic scenario, the vaccine moves forward to the next trial phases, it won't be widely available for years to come.

Myriam Johnstone, a Biomedical Research and Training Program Manager at the Black AIDS Institute, speculated that the distribution of an HIV vaccine "may unfortunately mirror the same issues we see with PrEP (pre-exposure prophylaxis) distribution" and cited worrying statistics.

Though PrEP, a one-a-day pill that lowers the likelihood of someone contracting HIV when they are exposed, is very effective, there have been issues with distributing it to communities which need it most.

According to the CDC, in 2018, Black Americans made up about 42% of new HIV cases but are only 13% of the general population. While Black Americans are disproportionately impacted, they are only 11% of PrEP users.

"We have to understand and address the structural and social determinants of health that predict quality and quantity of life, the systemic racism that riddles American economy and healthcare systems, and also the medical mistrust resulting from over 400 years of oppressive medicine practice on Black Americans," Johnstone said.

"It's not just about vaccines, it's about vaccines and masks and physical distancing, particularly in indoor settings. HIV is the same way. We need a comprehensive, integrated and sustained response." –Mitchell Warren

Ali Hayes, a sexual health educator who has worked in the field of HIV for more than two decades, echoed Johnstone's concerns and suggested that public health campaigns should be led by representatives from affected communities.

Another pressing issue Hayes brought up is the "stigma around HIV and other STIs." To counter that, Hayes suggested "integrating vaccine messaging and vaccine pop ups into spaces that you wouldn't normally see it, so that you can start to normalize it." Instead of relying on doctor's offices as the main place for vaccination, there should also be more discrete options so people don't feel anxious over being outed as LGBTQ, an IV drug user or sex worker.

Hayes pointed to the HPV vaccine as a model for how a vaccine that prevents STIs can eventually get normalized. Though at first the HPV vaccine was only recommended for sexually active women, the CDC now recommends that children from the ages of 9 to 12 get it.

If the last few months have taught us anything, it's that the anti-vaxx movement is very adept at using social media to widely spread disinformation. Timothy Caulfield, a spokesperson for the Canadian campaign ScienceUpFirst, said that for a potential HIV vaccine, one thing to look out for is how anti-vaxxers may mimic their COVID-19 strategy by casting doubt on mRNA technology. He speculated that anti-vaxxers may also borrow from their strategy with the HPV vaccines by spreading falsehoods about how it leads to infertility and promiscuity.

"We need social media platforms to take evidence-based strategies to slow the spread of misinformation on their platforms," he added. "That might include deplatforming when appropriate, but it might include other strategies to make sure that people have access to trustworthy information."

Even in a world with a vaccine, public health institutions would still need to promote other preventative methods. Mitchell Warren, the Executive Director of AVAC, said that "there will never be a single intervention for HIV." He noted that while at the moment, condoms and PrEP are great preventative measures, in the near future, upcoming methods such as injectable PrEP and PrEP vaginal rings can make a significant impact in stopping the spread.

Warren stressed that treating the 40 million people around the world with HIV shouldn't be ignored because when someone living with HIV has an undetectable viral load due to taking the proper medications, their risk of transmission is much lower.

Even if the prospect of a vaccine is exciting, eliminating the spread of HIV on a global scale will have to be a multipronged approach regardless of what happens. "It's just like what we're seeing with COVID," Warren added. "It's not just about vaccines, it's about vaccines and masks and physical distancing, particularly in indoor settings. HIV is the same way. We need a comprehensive, integrated and sustained response."

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