History of HIV Vaccines: Where Are We Now?

HIV is a virus that has been affecting people worldwide for decades. It gradually causes the immune system to fail. The immune system is your body's way of protecting you from things like viruses and bacteria.¹

People who have HIV are less protected from disease and infection. HIV is transmitted through very specific forms of contact with the bodily fluids of someone who is HIV positive. HIV can be transmitted through contact with:^1,2

• Blood
• Semen
• Vaginal fluid
• Breast milk
• Sexual contact
• Contact through open wounds, or objects such as needles

HIV cannot be transmitted through simple touch, surfaces, or the air.^1,2

The fight against HIV

In 2019, there were about 1.2 million people living with HIV in the United States. Even though HIV affects so many people, there is currently no cure for it. The virus changes too quickly and unpredictably to create a cure.^3,4

The main focus in the fight against HIV is prevention. The way HIV interacts with cells makes getting rid of the virus very hard. Some of the key problems are:^5-7

• HIV becomes a part of the cell it infects.
• Some infected cells can survive even the strongest treatments and continue to make more infected copies.
• The same treatments do not work to remove infected cells and prevent new cells from being infected.

Currently, pre-exposure prophylaxis (PrEP) treatments are used to help prevent HIV. PrEP uses antiviral drugs to help strengthen your cells against HIV. Antivirals are drugs used to treat different viruses.⁸

Creating a vaccine for HIV

Drugs used for PrEP, such as Truvada®, must be taken daily to protect you. Taking drugs daily can be costly and difficult to keep up with. An alternative answer is making a vaccine for HIV. One of the main goals of a vaccine would be longer-term protection at a lower cost.^8,9

Attempts at making an HIV vaccine have been going on since the beginning of the HIV/AIDS pandemic. The first clinical trials in the United States started in 1987. The trials recruited people who had taken part in high-risk behaviors but were negative for HIV.¹⁰

Making an HIV vaccine has proven very difficult. One of the main difficulties is related to the process of making vaccines. Most vaccines copy the way the target virus attacks. This helps your cells be prepared for an actual encounter with a virus.⁹

The earliest vaccines tried to copy different parts of the virus itself. For example, researchers tried to copy the outer layer of the virus. If cells could learn to identify that layer, they could find and remove HIV before it entered healthy cells. The structure of HIV is very complex. That made it harder to use this approach to create a vaccine.^9-12

Another approach is a vaccine that works with the cells most targeted by HIV, T cells. T cells are a part of the immune system. These types of vaccines have been successful in controlling infection, but they struggle to remove it completely.^9,11,12

What we continue to learn

Modern vaccines use what we constantly learn about HIV to improve these approaches. As vaccine technology grows, researchers also adopt new methods, such as mRNA vaccines. mRNA vaccines work by telling your cells how to make parts of the target virus that your immune system can detect and defend against.^12-14

As we get closer to a vaccine for HIV, new challenges also arise. The popular use of PrEP requires special considerations to be made in clinical trials. It is important to learn how using PrEP with a vaccine can affect the way the body will interact with the virus.^12,14

The fight against HIV and AIDS is ongoing. Although people continue to be diagnosed, great leaps have been made in medicine to help people with HIV live healthy lives. Continuing advances in vaccine technology help us get closer to even better protection.