PrEP vs PEP

About HIV

HIV (human immunodeficiency virus) is a virus that attacks your immune system, specifically “CD4 cells”, which are involved in your immune system’s “memory” of past infections. As the CD4 cells get destroyed, you are likely to get more severe infections. If left untreated, HIV ultimately results in AIDS (acquired immunodeficiency syndrome), which is life-threatening due to the destruction of the immune system.

There are many situations that put people at risk of transmitting HIV.

• Anal sex
• IV drug use
• Unprotected sex
• Sex with multiple partners

Read more about HIV

Preventing HIV

There are ways to help prevent HIV transmission, such as using barrier condoms during sex or not sharing needles when using IV drugs can help reduce the risk of transmission.

However, accidents happen. For instance, a healthcare worker might accidentally prick themselves with a used needle at work. Or, some individuals continue engaging in risky behaviors despite the associated dangers. In such cases, there are medications available to prevent transmission and to help reduce the risk of contracting HIV after exposure.

PrEP and PEP

Pre-exposure Prophylaxis (PrEP) and Post-exposure Prophylaxis (PEP) are strategies used to prevent the transmission of HIV, but they are applied at different times and for different purposes. PrEP is used before the exposure to the virus, while PEP is used after you have been exposed to HIV.

PrEP (Pre-exposure prophylaxis)

PrEP involves taking antiretroviral medications before potential exposure to HIV. The consistent presence of the medication in your bloodstream can prevent the virus from establishing itself and spreading within your body. When used consistently, PrEP can reduce the risk of HIV infection by up to 92 percent.

There are three PrEP medications approved by the FDA: Truvada (oral), Descovy (oral), and Apretude (injectable).

Truvada

• Administration: once daily by month
• Active ingredients: emtricitabine (FTC) + tenofovir alafenamide (TDF)
• Truvada was a groundbreaking medication for PrEP and has shown to be effective in reducing the risk of HIV transmission when taken as prescribed

Descovy

• Administration: once daily by month
• Active ingredients: emtricitabine (FTC) + tenofovir alafenamide (TAF)
• A newer version of Truvada
• TAF is associated with lower levels of tenofovir in the bloodstream, which might result in reduced kidney and bone toxicity compared to TDF (found in Truvada)
• Descovy is not approved for use in females at risk of contracting HIV through vaginal sex

Apretude

• Administration: injection once per month for the first two months, then every other month for the remainder of the treatment by a healthcare provider
• Active ingredients: cabotegravir
• First long-acting injectable PrEP, approved in December 2021

PEP (Post-exposure prophylaxis)

A short course of antiretroviral medication taken soon after (within 72 hours) a possible exposure to HIV. It is used for 28 days following exposure. PEP typically includes multiple medications, as the amount of virus in the body is higher than needed with pre-exposure prophylaxis.

PEP is only used on an as-needed basis in emergency situations. It is not intended for regular use in people who are at risk of HIV infection.

The most common PEP regimen includes Truvada (tenofovir, emtricitabine) and a third drug, either dolutegravir or raltegravir. There are alternative medication combinations for different circumstances, and most invlove three drugs.

How Do They Work?

Once you are exposed to HIV, the virus starts to replicate and grow very quickly in your body. The first few days to weeks are critical for the virus to “set up shop” inside your body, taking a toll on your immune cells and a permanent residence in your body. The way PEP and PrEP work are very similar, as they both work to combat the virus early on while the number are still low, in attempt to prevent a permanent infection.

The main difference is the timing of the medication in the course of the infection. In the case of PrEP, you are taking the medication before you come into contact with HIV. If you come into contact with HIV, there will already be medication in the body to fight off the infection before it can mount a proper attack on your body. Ideally, the PrEP will eradicate the virus before an infection settles in. This is why this medication is a good option for individuals who are at increased risk of HIV infection.

In contract, PEP is more of a “rescue” medication. For individuals who are not at increased risk of HIV, taking PrEP everyday doesn’t make sense. But there is still an option if you have suspected or confirmed contact with HIV: PEP, the slightly more intense medication, is started in the first 72 hours after being exposed. This allows the medication to combat the virus while its numbers remain low in the body, giving it a good chance of preventing a permanent infection.

Who Should Use PrEP?

PrEP is a long-term strategy for HIV prevention. It should be used for individuals who are at increased risk of transmitting HIV through sex.

• Individuals who have sex in exchange for drugs/money
• Individuals who have sex with people who have unsuppressed HIV
• Individuals who have unprotected sex with multiple partners

Even if you use PrEP, it’s important to maintain other safe sex practices, including the use of condoms and regular sexual health testing.

Who Should Take PEP?

If you have had a known or suspected exposure to HIV from any source and are within the 72-hour timeframe, you most likely qualify for post-exposure prophylaxis to reduce your chances of contracting HIV. PEP is often warranted for situations that don’t occur regularly, including after:

• Sexual assault
• Being accidentally pricked by a used needle (this often occurs at work in the healthcare industry. May also apply to accidentally sharing needles for drug use)
• Having unprotected sex with someone of unknown HIV status (unsuppressed HIV infection)
• Sharing a needle to inject drugs (with someone of unknown or known unsuppressed HIV status)

If you find that any at risk situations occur regularly, such as frequently having unprotected sex, you may consider taking PrEP in order to prevent exposure, rather than medications post-exposure.