New Analysis Estimates Future Course of U.S. HIV Epidemic

As described in the July 14, 2010 advance online edition of the Journal of Acquired Immune Deficiency Syndromes, researchers from the U.S. Centers for Disease Control and Prevention (CDC) and Johns Hopkins Bloomberg School of Public Health have new estimates of future HIV incidence (new cases), prevalence (total cases), and infections averted under a variety of scenarios including stepped-up prevention interventions. They found that HIV prevalence will likely increase over time unless greater attention is devoted to preventing new infections.

H. Irene Hall from the CDC and colleagues developed mathematical models to estimate the potential future burden of HIV in the U.S., looking at incidence, prevalence, and infections averted over the next 10 years.

The researchers used the 2006 HIV incidence estimate of 55,400 new infections per year, prevalence of 1,107,000 people living with HIV, and a transmission rate of 5.0 per 100 HIV positive people. They made estimates based on 5 scenarios, 3 of which were base-case scenarios assuming steady HIV incidence, a steady transmission rate, and a declining transmission rate relative to the 2000-2006 trend. The other 2 scenarios assumed intensified HIV prevention interventions that would reduce transmission by 50% over either 5 or 10 years.

Maintaining HIV prevention efforts at the current level would result in substantially more people living with HIV in 10 years, along with healthcare costs to provide care and treatment to individuals who become infected within the next decade, according to a summary of findings in the CDC Division of HIV/AIDS Prevention's E-HAP newlstter.

The base-case scenarios predicted that HIV prevalence would increase 24%-38% over 10 years. Reducing the transmission rate by 50% within 10 years would reduce incidence by 40%, but prevalence would still increase by 20%, reaching an estimated 1,329,000 people living with HIV. Under the intensified 5-year scenario, annual HIV incidence would decrease by 46%, from 55,400 to 30,200 new infections, saving more than $100 billion in healthcare costs.

"Although in year 10 incidence is similar regardless of the intervention time frame, more infections are averted when halving the transmission rate within 5 years," the study authors wrote.

The JAIDS study shows that "the faster we act, the more lives and money we can save," according to the CDC synopsis. "Intensifying the nation's HIV prevention efforts would significantly reduce the number of annual new infections and potentially save hundreds of thousands of lives."

A CDC fact sheet describing the study and future estimates in more detail is available at

"The release of the National HIV/AIDS Strategy in July 2010 gives the HIV prevention community an opportunity to redefine our nation's approach to HIV prevention and calls for shared responsibility to end the U.S. epidemic," according to the CDC fact sheet. "Modeling studies, such as this one, can help guide appropriate actions as we collectively move forward to implement the National HIV/AIDS Strategy."

"It is clear that progress will require us to direct available resources to the populations and geographic areas with the most urgent needs," the agency continues. "Additionally, we must expand HIV prevention efforts for individuals at the highest risk of HIV transmission and infection; ensure a focus on community-level interventions that address underlying HIV risk factors in hardest-hit areas; and work to ensure basic, fundamental HIV knowledge among all Americans."

Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA; Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA.



HI Hall, TA Green, RJ Wolitski, J Mermin, and others. Estimated Future HIV Prevalence, Incidence, and Potential Infections Averted in the United States: A Multiple Scenario Analysis. Journal of Acquired Immune Deficiency Syndromes. July 14, 2010 (Epub ahead of print).

Other Sources

CDC Division of HIV/AIDS Prevention. E-HAP Newsletter. August 10, 2010

CDC. Projecting Possible Future Courses of the HIV Epidemic in the United States. Fact sheet. August 2010.