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Pre-exposure prophylaxis important to stopping spread of HIV :

September 25, 2019

Editor’s note:This is the first of two articles on pre-exposure prophylaxis (PrEP) for HIV control. The second article will discuss the specifics of PrEP in adolescents and adults.

More than 38,000 new HIV infections were reported in 2017 in the United States. In an effort to end the HIV epidemic, the U.S. Department of Health and Human Services has proposed to reduce new HIV infections by 90% by 2030.

Although rates of new HIV infections have declined among heterosexuals, people who inject drugs and white men who have sex with men (MSM), declines have not been detected among black MSM and increases have been reported among Latino MSM.

One aspect of controlling the spread of HIV focuses on protecting people at risk for HIV infection by using antiretroviral medications as PrEP.

In 2017, the Centers for Disease Control and Prevention (CDC) updated guidance for PrEP for the prevention of HIV infection in the U.S. ( The U.S. Preventive Services Task Force (USPSTF) recently published recommendations for PrEP for those at increased risk of HIV infection (JAMA. 2019;321:2203-2213).

The importance of PrEP is greatest in communities with a high prevalence of HIV infection (see map).

Which of the following statements are true?

a) More than 80% of new HIV infections reported in 2017 occurred in males.

b) Approximately 1.1 million people in the United States are living with HIV.

c) The USPSTF recommends screening adolescents and adults ages 15-65 years for HIV infection as well as younger adolescents who are at increased risk of infection.

d) The USPSTF recommends screening all pregnant women for HIV infection, including those who present in labor or at delivery with unknown HIV status.

Answer: All statements are true.

The CDC and the USPSTF have made recommendations to decrease the risk of acquiring HIV infection as well as other sexually transmitted infections in high-risk settings.

Recommendations include abstinence, reducing the number of sex partners, consistent condom use and HIV PrEP with tenofovir disoproxil fumarate/emtricitabine (Truvada). Postexposure prophylaxis (PEP), started as soon as possible after a possible exposure, may decrease the risk of HIV infection. Counseling to reduce risky behavior is encouraged.           

Although generally treatable, an HIV infection cannot be cured. PrEP is one option to reduce the risk of viral transmission. The USPSTF recommends PrEP for those at increased risk due to sexual acquisition or injection drug use. Transgender females and males who are sexually active are at particular risk of HIV infection.

When taking PrEP daily, the risk of acquiring HIV is reduced by about 99% among MSM. While daily use is recommended, taking PrEP at least four times per week may provide similar protection among MSM. A few cases of new HIV infections have been reported with PrEP verified adherence, indicating that the risk is not eliminated.

Among heterosexual men and women, there is evidence for effectiveness of PrEP, suggesting protection is likely to be similar to that observed for MSM. Data show that it takes about 13 days longer to reach a maximum drug level of PrEP in vaginal tissue as compared to rectal tissue. Once maximum drug levels are reached, the effectiveness of PrEP in preventing acquisition during sex is expected to be similar for vaginal or anal sex and for men and women.

Promoting consistent condom use is an important component of a successful PrEP program. Proper and consistent condom use decreases the risk of HIV infection by approximately 80%. Optimal use of condoms means both consistent and correct use during every sex act. Laboratory studies show that latex-based, polyurethane or other synthetic material-based condoms provide an impermeable barrier to passage of HIV. However, condoms may not offer complete protection due to the chance of product failure.

Based on observational studies among adult males, there is insufficient evidence to conclude that male circumcision reduces the risk of acquiring HIV for the insertive partner or for the receptive partner during anal sex among MSM. However, limited data suggest male circumcision reduces the risk of heterosexual men acquiring HIV during sex by 50%.

People who inject drugs risk acquiring an HIV infection from both injecting and sex behaviors. Limited studies suggest that PrEP reduces the risk of acquiring HIV by an estimated 75% when used consistently.

Dr. Meissner is professor of pediatrics at Floating Hospital for Children, Tufts Medical Center. He also is an ex officio member of the AAP Committee on Infectious Diseases and associate editor of the AAP Visual Red Book.

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