Most New HIV Cases Stem From People Undiagnosed or Untreated

Megan Brooks

March 19, 2019

About 80% of new HIV infections in the United States occur in about 40% of people who either don't know they are infected or are not receiving HIV care, according to a report released today by the Centers for Disease Control and Prevention (CDC).

The remaining 20% of new infections occur in people who are receiving care for HIV infection but who were not virally suppressed.

"These new Vital Signs data show the tremendous impact we can have by helping all Americans living with HIV know their diagnosis, quickly get into treatment, and remain in care to stay healthy," CDC Director Robert R. Redfield, MD, said in a news release.

Zihao Li, PhD, and colleagues at the CDC used surveillance data to create a mathematical model to estimate HIV transmission rates in 2016 along the HIV continuum of care from infection to treatment and viral suppression.

The overall estimated HIV transmission rate in 2016 was 3.5 new infections per 100 person-years. The rates of transmission decreased with progression along the HIV continuum of care, the authors report.

People who are acutely infected but who are unaware of their infection have the highest transmission rate (16.1 per 100 person-years), followed by people nonacutely infected and unaware (8.4 per 100 person-years). These two groups account for 15% of people with HIV and about 38% of new HIV transmissions, the model shows.

The transmission rate among people who are aware of their HIV infection but who are not receiving care is 6.6 per 100,000 person-years. This group makes up 23% of people with HIV and accounts for 43% of new transmissions. People who are receiving HIV care but who are not virally suppressed (11%; transmission rate, 6.1) account for 20% of new HIV infections.

Notably, say the researchers, the rate of transmission was zero among the 51% of HIV-infected people who are taking antiretroviral therapy and are virally suppressed.

"Bold but Achievable"

The report was published online March 18 in the Morbidity and Mortality Weekly Report to coincide with the opening of the CDC's 2019 National HIV Prevention Conference in Atlanta, Georgia.

Ensuring that more people are tested and are receiving HIV care is the foundation of the recently announced federal initiative, Ending the HIV Epidemic – A Plan for America, Admiral Brett P Giroir, Health and Human Services assistant secretary for health, noted during a briefing with reporters.

The ambitious plan, announced last month, aims to reduce HIV infections in the United States by 75% within 5 years and by 90% within 10 years.

"HIV has cost America too much for too long," said Giroir. He noted that 700,000 Americans have died of AIDS since 1981, and another 400,000 Americans are at risk of becoming infected with HIV this decade "if we accept the status quo."

The plan to end the HIV epidemic in America is "bold but completely achievable," he said, "because we have the right tools, the right data, and the right leadership."

"Diagnose, treat, protect, and respond: These are the key strategies in our historic initiative to end the HIV epidemic in America by engaging all the people at risk into comprehensive prevention strategies," Redfield stated in the release.

The CDC advises providers to screen patients aged 13 to 64 years for HIV infection at least once and to test some patients more frequently (annually for those at high risk; every 3 to 6 months for sexually active gay and bisexual men); to rapidly link, engage, or reengage patients into comprehensive HIV care; and to encourage patients to sustain viral suppression for their own health and because of the prevention benefits.

"Today, we have the tools to end the HIV epidemic," Jonathan Mermin, MD, director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, said in the release. "But a tool is only useful if it's in someone's hands. This is why it's vital to bring testing and treatment to everyone with HIV — and to empower them to take control of their lives and change the course of the epidemic."

MMWR Morb Mortal Wkly Rep. Published online March 18, 2019. Full text


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