The majority of new HIV infections are transmitted through either patients who are unaware of their HIV status or from those who are aware of their infection, but are not in care, researchers found.
A mathematical model estimated that patients with undiagnosed HIV infections, and those with diagnosed HIV infections not in care, accounted for approximately 80% of new infections in 2016, reported Zihao Li, PhD, of the CDC in Atlanta, and colleagues, in Vital Signs, an early release of the Morbidity and Mortality Weekly Report.
Early HIV diagnosis and treatment are cornerstones of the recently announced plan to end the HIV epidemic in the U.S. by 2030. Indeed, a call with media on Monday used the new research as evidence that supported the implementation of this plan.
Jonathan Mermin, MD, director of the CDC National Center for HIV/AIDS, Viral Hepatitis, STD, and TB stated that Monday’s report, “highlights the gap preventing us from stopping HIV infections” and “emphasizes the impact HIV resources could have if we expanded HIV testing and treatment.”
U.S. Surgeon General VADM Jerome Adams, MD, MPH, went over the proposed funding for this initiative, stating that $291 million has been requested for Fiscal Year 2020. These funds will hope to finance “extra boots on the ground and resources to address the HIV epidemic,” he said.
But members of the media remained skeptical about the plan, with some suggesting that other HIV experts estimated an initiative of this scale would cost billions, not millions of dollars. One reporter even said that the proposed figure “doesn’t begin to tickle the toes” of combatting the HIV epidemic, especially given the cost of pre-exposure prophylaxis (PrEP), unless the administration was planning on cutting the price of drugs.
CDC Director Robert Redfield, MD, responded that this was a “multi-year initiative,” and could not release all the details of the plan at the present time. He added that the agencies who spent the last 6-7 months putting the plan together are cognizant of the issues involved.
“We’re going to get this plan done,” Redfield said.
Li and colleagues analyzed data from the National HIV Behavioral Surveillance and the National HIV Surveillance System in a mathematical model to estimate transmission rates along the HIV continuum of care. Overall, they found the HIV transmission rate was 3.5 per 100 person years in 2016, and estimated that overall transmission had declined from 2010 (4.5 per 100 person years), mainly due to a “steady increase” in viral suppression.
But transmission rates varied significantly, depending on where patients were on the continuum of care. Overall, 33.6% of transmissions occurred by those who were “not acutely infected and unaware of their infection” and 42.6% were among those who were “aware of their HIV infection, but not in care.”
Importantly, the percentage of transmissions among those taking antiretroviral therapy and virally suppressed was 0%, the authors noted.
About three-quarters of estimated transmissions were among men who have sex with men (MSM), and about 10% were among people who inject drugs. MSM also unsurprisingly had the highest transmission rate (4.4 per 100 person years).
Interestingly, while the highest transmission rate was highest among persons ages 12-34, the authors said, adults ages ≥55 had the highest portion of new infections (29.4%).
The authors noted that “providers play an important role” by “screening patients for HIV infection, linking patients to care and emphasizing the importance of achieving and maintaining viral suppression for personal health and prevention benefits.”
“Routine testing and targeted HIV testing are complementary approaches to addressing the 38% of transmissions that occurred from the estimated 15% of persons with undiagnosed HIV infection,” the authors wrote.
On the call, Redfield addressed what he termed “diagnostic complacency,” saying that patients were seeing the doctor, but were not being diagnosed, despite CDC recommendations for HIV testing.
He said that some of that gap could potentially be filled with “innovation in diagnostic” testing in “non-traditional, non-clinical settings,” such as testing kits ordered “over the Internet.”
Redfield also discussed how the new HIV initiative would help with identification and treatment of infections by working with communities, local health systems, and public health leaders to “[scale] up support systems for people to get the HIV care they need and stay in HIV care.” The plan would also include improved access to prevention measures, such as PrEP, condoms, and syringe disposal services.
“Science that sits on the shelf has no value. Today’s … data highlights my point,” Redfield said. “It underscores the tremendous impact we could have by focusing on diagnosis and treatment.”
Li and co-authors disclosed no relevant relationships with industry.