Is There a Vaccine for HIV?

After the human immunodeficiency virus (HIV) was first discovered as the cause of AIDS in 1984, researchers vowed to find a cure. But what they had yet to discover was that HIV is a complex virus. Much more had to be learned about the human immune system and the virus itself before a vaccine could be made.

Since then, significant advancements have been made in how the infection is treated, but researchers have yet to develop an HIV vaccine. And, although new HIV cases have gone down significantly since the mid-1980s, HIV infection remains a major public health concern, and a vaccine is still needed.

Here, we’ll discuss the latest research for an HIV vaccine and if we can expect one to be available soon.

Why isn’t there a vaccine for HIV?

This is the million-dollar question. In fact, it’s a $16 billion question. Over $16 billion was spent between 2000 and 2020 on research toward finding an HIV vaccine.

Factors that affect HIV vaccine progress include:

• Money: HIV is a lot more complex than researchers initially thought. Because of this, developing a vaccine has taken a lot more time, which means that considerably more funding has been needed than expected.

• Finding participants: Participants are needed to test vaccines in studies before they are brought to market. However, potential study participants may be concerned about the safety of these trials. Protecting vaccine participants is the top concern for any research study, though. The HIV Trials Network and other organizations make sure participants are treated respectfully and kept safe.

• The perception around the locations of study sites: Vaccine research is ongoing internationally, including studies that take place in developing countries. Some argue that conducting these studies takes advantage of these communities. However, others see the benefit of studying the virus and vaccine in groups of people who have been hit hardest by the HIV epidemic.

When HIV was discovered, researchers had high hopes for developing a vaccine. But it has taken a while for science to catch up.

Next, let’s dive more into why developing a vaccine for HIV has been more difficult than first thought.

Why is developing a vaccine for HIV more difficult than for other diseases?

Most vaccines work in a similar way to one another. When administered, a vaccine causes the immune system to recognize a particular invader, like a virus. Then, the immune system can develop antibodies, which protect your body if it sees that invader in the future.

Common ways that vaccines are made include inactivating the virus, weakening the virus, using pieces of the virus, or combining the virus with something else. All of these methods can introduce the immune system to the virus — so the immune system can make protective antibodies — without making a person sick.

HIV has many characteristics that make vaccine development difficult, including:

• Subtypes and mutations: There are many mutations (changes) that make the virus a moving target for researchers.

• No natural immunity: This means that, unlike with other infectious diseases, people don’t usually “recover” from HIV if they are infected.

• Unknown level of immunity needed: Researchers have not discovered what level of immunity would actually be protective. In other words, we don’t know how many antibodies are necessary and which part of the immune system to activate.

• No animal models for research: A useful animal model for HIV research does not exist. This limits researchers from testing possible vaccines before exposing them to people.

Are there any HIV vaccines in the works?

Yes. Even with the setbacks mentioned above, research is moving forward. There are two different types of vaccines in the works: preventative vaccines and treatment vaccines.

Most of the vaccines we receive today are preventative, meaning that they are given before we are exposed to a germ, to better prepare us if we later encounter it.

A preventative HIV vaccine would be given to people before contracting the virus. It would work by alerting our immune system, triggering it to create antibodies and other memory cells against the virus. This means that our immune system could mount a targeted response if exposed to HIV in the future.

On the other hand, a treatment vaccine would be for people who are already infected with HIV. It would help to lessen HIV symptoms, lower the need for HIV medications, and make it less likely to spread HIV to others.

Quite a few vaccines are in different stages of development. An exact number is difficult to nail down. However, there are a few ways to estimate.

How many HIV vaccines are in clinical trials?

There is currently a vast research network related to HIV trials. There are more than 800 trials related to HIV vaccines alone. These trials are in different stages of their research. Over 60 studies are just beginning and looking for study volunteers. Other studies have finished collecting data and are looking into their results. Many studies have already been published.

RV144 study

The first study to show promise in preventing HIV was the RV144 study in Thailand. While this vaccine candidate did show some benefit, it was only 31% effective in lowering HIV infection.

HVTN 702 study

The HVTN 702 study took the lessons learned from the earlier RV144 study in hopes of making a more effective vaccine. However, an interim analysis in early 2020 showed that the vaccine was not effective at preventing HIV. Study participants will continue to be followed, but no additional shots will be given.

Mosaic vaccine studies

There are also two large international studies that showed promise. Both of them use mosaic vaccines — vaccines that contain several components (parts) from many HIV strains — to trigger an immune response against several common HIV types.

The first study, called Imbokodo, used a mosaic vaccine meant to prevent HIV infection in adult women. Participants in the study got the vaccine 4 times over 1 year. But an initial analysis showed that the vaccine couldn’t prevent HIV. So, the study was discontinued.

The second study, known as Mosaico, also uses a mosaic vaccine. The study includes cisgender men and transgender people who have sex with cisgender men and/or transgender people. Participants get the vaccine 4 times over 1 year, similar to Imbokodo. This study is still in progress, and we may not see results until 2024.

HVTN 302 study

The HVTN 302 trial is studying three different HIV vaccines that use mRNA technology similar to the Pfizer and Moderna COVID-19 vaccines. But instead of making the spike protein from SARS-CoV-2 (the virus that causes COVID-19), it’s the spike protein from HIV. This helps teach your immune system to recognize and fight HIV if you’re exposed to it in the future.

As of 2022, the HVTN 302 trial is a small study that’s primarily focusing on safety. Results are expected in 2023.

Are any live virus vaccines for HIV in the works?

No. The HIV vaccines in development do not contain live viruses and will not give you HIV. Some vaccines (for diseases other than HIV) use a weakened form of virus to cause your body to develop immunity. This is not the case for HIV vaccines.

Most HIV vaccines being developed use a less dangerous virus that delivers instructions for the body to make an HIV protein. The HIV protein triggers the immune system to get rid of it, creating memory immune cells in the process. Over 30,000 participants have taken part in HIV vaccine trials, and none have contracted HIV from the vaccine.

What is the difference between preexposure prophylaxis (PrEP) and an HIV vaccine?

People can take medications to lower their risk of infection before coming into contact with HIV. This method of preventing HIV is known as preexposure prophylaxis, or PrEP.

An HIV vaccine would also prevent someone from getting HIV if exposed, but it would likely make a much larger impact on the HIV epidemic overall than PrEP alone.

Even though some of the medications used for PrEP are also used to treat HIV, they are used differently for each indication. PrEP is used before a possible exposure by someone who might be at risk of contracting the virus. HIV treatment, on the other hand, includes a combination of medications to lower the amount of virus in the body in someone who already has HIV.

Next, we’ll talk about PrEP and how it differs from an HIV vaccine.

What is PrEP?

PrEP is a method to prevent HIV in people who might be at risk for infection. PrEP might be prescribed in people without HIV who:

• Inject non-prescription drugs, especially if needles or syringes are shared

• Have unprotected sex with a partner who is HIV positive

• Have had a sexually transmitted infection in the past 6 months

Truvada and Descovy are oral pills used for PrEP. Apretude is a newer, long-acting injectable option. PrEP is very effective for preventing HIV infection before exposure. In fact, it’s up to 99% effective when used for preventing HIV from sexual contact. But you’ll need to take it for a specific amount of time before you’re protected. Its effectiveness will also depend on the type of sex you’re having.

We know less about how effective PrEP is for preventing HIV from injecting drugs. Some reports state that it’s at least 74% effective in this case, but more research is needed.

There are a few different ways to use PrEP, but the most common is taking medication every day. If a person is considering PrEP, they must first get an HIV test. The HIV test must be negative to use PrEP.

Once you decide to use PrEP, it’s important to take it as directed by your healthcare provider. Regular follow-up visits are also required. The follow-up visits are to check for HIV and refill your medication (or receive another injection) if you’re negative.

How is PrEP different from a vaccine?

PrEP may not be an option for everyone.

Reasons that PrEP may not be for you include:

• Cost, since the medications can be expensive

• Barriers to getting the needed medication

• Needing to take the medication every day

• Side effects

PrEP is also not 100% effective in preventing HIV. So, although PrEP would be an important preventative strategy, a vaccine would likely be a more accessible and impactful option, overall.

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Written by:

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP, has over a decade of experience as a pharmacist, professor, and researcher. She was a full-time clinical professor in the pharmacy practice department at D’Youville School of Pharmacy before subsequently joining the faculty of the pharmacy practice department at the University at Buffalo School of Pharmacy and Pharmaceutical Sciences.

Edited by:

Samvida Patel, MNSP, INHC

Samvida Patel, MNSP, INHC, is a health editor at GoodRx. She is a nutritionist and integrative nutrition health coach with over 8 years of experience in health communications.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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Co-contributors: Timothy C. Hutcherson