March 18, 2019
2 min read

80% of new HIV cases transmitted by undiagnosed or untreated people

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Photo of Robert Redfield
Robert R. Redfield

In 2016, more than 80% of new HIV infections in the United States were transmitted by individuals who either did not know they were infected with HIV or had been diagnosed but were not receiving care, according to data released on the first day of the National HIV Prevention Conference in Atlanta.

Health officials said the findings, which were published in a CDC Vital Signs report, show that gaps in HIV testing and treatment are getting in the way of preventing new infections.

Increasing the number of individuals tested and providing HIV treatment are key components of the proposed federal plan to reduce the number of new HIV infections by 90% in 10 years.

“I believe that the right investment in the right placement using the right strategies, when we return in 10 years to the National HIV Prevention Conference, we will be talking about what we did all together to eliminate new HIV diagnoses in the United States, not what we could do,” CDC Director Robert R. Redfield, MD, said during a telebriefing.

Findings in the new report were based on updated estimates from the CDC’s Progression and Transmission of HIV (PATH 2.0) model.

In 2016, approximately 15% of people with HIV in the U.S. did not know they were infected, and these individuals were responsible for 38% of new transmissions, according to the report. Almost a quarter — around 23% — of people knew they were infected with HIV but were not receiving treatment, and they accounted for 43% of new transmissions. Individuals who were receiving care but not virally suppressed made up 11% of the HIV-infected population and caused 20% of new infections.

HIV-positive individuals who were receiving treatment and were virally suppressed made up 51% of the population and were responsible for no new transmissions, according to the findings.

Researchers found that 73% of new HIV transmissions were generated by MSM, 9.8% by those who inject drugs, 5.3% from MSM who inject drugs, and around 12% from heterosexual men and women.

Transmission rates were highest in people aged 13 to 24 years in general, but individuals aged at least 55 years accounted for the largest percentage of new infections at 29.4%, the researchers reported.

“Today, we have the tools to end the HIV epidemic, but a tool is only useful if it is in someone’s hand,” Jonathan H. Mermin, MD, MPH, director of the CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, said during the briefing. “These data emphasize why it’s vital to bring testing and treatment to everyone with HIV. We can empower people with HIV to take control of their lives and change the course of this epidemic.”– by Erin Michael


CDC. Gaps in HIV testing and treatment hinder efforts to stop new infections. Accessed March 18, 2019.

Zihao L, et al. MMWR Morb Mortal Wkly Rep. 2019;doi:10.15585/mmwr.mm6811e1.

Disclosures: The authors, Mermin and Redfield report no relevant financial disclosures.