An estimated 1.2 million Americans are living with HIV, a virus that attacks the body’s immune system, and while new infections have declined significantly since the peak of the HIV epidemic,  31,800 people were newly diagnosed in 2022, according to the most recent data from the Centers from Disease Control and Prevention (CDC).

There is currently no vaccine available for HIV, however over the past decade, the breakthrough medication PrEP (pre-exposure prophylaxis) has driven down the rates of transmission. PrEP prevents the virus from taking hold and spreading throughout the body, and when taken correctly, reduces the risk of getting HIV from sex by 99%. It does not protect against other sexually transmitted infections (STIs) like syphilis and gonorrhea, so it’s advised with condom use and frequent HIV and STI testing.

“Since PrEP became available in 2012, we have seen a significant reduction in new HIV diagnoses in New York City and the world,” says Caroline Carnevale, a nurse practitioner at NewYork-Presbyterian/Columbia University Irving Medical Center. “It has also provided many people with relief from worrying about HIV transmission in their sex lives.”

PrEP uptake has increased steadily since it was approved by the Food and Drug Administration (FDA), but more progress is needed, says Carnevale. The CDC estimates that about 300,800 people were prescribed PrEP in 2020, representing only 25% of those who could benefit from the medication. Racial disparities also persist — 13% of Black and 24% of Latino people who could benefit from PrEP were prescribed it in 2022, compared to 94% of white people.

Scientists are hopeful that a new form of PrEP now in the final stages of FDA approval will be a game changer. The medication, called lenacapavir, is a biannual injection that has been remarkably effective — a recent clinical trial conducted across 88 sites in seven countries found that the medication provides near 100% protection from HIV.

Carnevale shares what to know about PrEP.

PrEP Comes in Three Forms

There are three different options for taking PrEP that are approved by the FDA: a daily pill, long-acting injectable, or on-demand. PrEP works by blocking the HIV virus from attaching to cells, preventing the virus from replicating and causing an infection.

The two pills approved for PrEP are called Truvada (emtricitabine tenofovir) and Descovy (emtricitabine tenofovir alafenamide). The long-acting injectable form, Apertude (cabotegravir), was approved in 2021 as a single intermuscular shot given every two months. “The injectable form of PrEP is equally as protective against HIV as the daily pill, if not more so, because you don’t have to worry about taking a pill regularly,” says Carnevale.

On-demand PrEP is for people who want to plan for protection around a sexual encounter. It is taken in a series before and after sex — two pills between two to 24 hours before sex, one pill the day after, and another pill the day after that (2-1-1). Unlike the other forms of PrEP, on-demand PrEP is only approved to be used when taking Truvada and, in the U.S., it is only approved for use for men who have sex with men.

PrEP Is Safe for Everyone, Including Pregnant People

“There are no qualifications for starting PrEP,” says Carnevale. “It is for anybody who wants it and is sexually active and does not have HIV.”

PrEP is safe to use during and after pregnancy. And for people with an HIV-positive partner who has an undetectable and untransmittable viral load, PrEP adds a layer of protection.  

A health care provider must prescribe PrEP and will schedule health screenings with HIV and STI testing regularly, depending on the prescription — for the PrEP daily pill it’s every three months, and for the long-acting injectable form of PrEP, it’s every two months. 

Some people taking PrEP may have minimal side effects, like nausea or headaches, but they are usually not serious and often get better over time. “Adverse effects like that are very rare,” says Carnevale. “It is really, really safe and effective.”