Making HIV Transmission a Rare Event

Although researchers have found a lack of effective treatment and diagnosis in many patients with HIV, they find how to greatly reduce virus transmission.


About 80% of new HIV transmissions are from people who do not know they have HIV or are not receiving regular care, according to a CDC report. That makes improvements in early detection and “rapid entry into care” key to ending the HIV epidemic within 10 years—the current US Department of Health and Human Services goal.

Recent studies have shown that viral suppression prevents sexual transmission of HIV, the researchers say. The studies found no HIV transmissions attributable to sex between HIV-discordant couples when the HIV-infected partner was maintaining viral suppression through treatment—even when the HIV-negative partner was not using preexposure prophylaxis. Those findings mean HIV transmission can become a “rare event,” the researchers say.

Today’s treatments have gotten simpler than the hills of pills that patients used to take. Sometimes the patient needs only a single-tablet regimen. Most people, according to the CDC, can achieve viral suppression within 6 months of starting treatment.

But many of the 1.1 million people with HIV infection are not effectively treated. In 2015, the CDC researchers say, 14.5% of people with HIV infection did not have a diagnosis, and 37.2% were not in care (receiving ≥ 1 CD4 tests in a measurement year). Nearly half were not virally suppressed. Lack of effective treatment results in worse outcomes and higher rates of transmission: It was associated with 38,700 new HIV infections in 2016.

The researchers used a model to estimate transmission rates in 2016 along the HIV continuum of care. Overall, the rate was 3.5 per 100 person-years. Among 9,600 people who were acutely infected and unaware of their infection, the rate was 16.1 per 100 person-years. Among 154,400 people who were nonacutely infected and unaware, the rate was 8.4.

Of the nearly 250,000 people who were aware of HIV infection but not in care, 16,500 transmissions were generated (6.6/100 person-years). Among the 125,300 who were receiving HIV care but not virally suppressed, 7,700 transmissions were generated (6.1).

The transmission rate was 0 for patients who were virally suppressed. The researchers note that 100% efficacy was assumed based on trial results for sexual transmission; no data are available on the efficacy of viral suppression on reducing HIV transmission from IV drug use.

Better detection and linkage to treatment will address most of the problem, but what about the patients who do not maintain viral suppression? Among patients in clinical care, about 80% were virally suppressed at their most recent visit, but about one-third did not sustain viral suppression over 1 year. For those patients, the researchers say, a tailored approach aimed at the barriers that are most relevant for the patient is critical to improving adherence.

The CDC recommends routine screening of all Americans aged 13 to 64 years at least once in their life and at least annual testing for those at high risk. In addition, the researchers say, it is important to spread the word that maintaining viral suppression prevents sexual transmission. Sharing this knowledge more generally might reduce the stigma associated with HIV and help engage patients in consistent care.

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