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Best In Science

New HIV Test Revises Epidemic Trends

Accurately tracking the HIV epidemic is essential to the nation’s HIV prevention efforts. Monitoring trends in new HIV infections has posed a major challenge, since the beginning of the epidemic, in part because many HIV infections are not diagnosed until years after they occur.

CDC has developed a new technology called serologic testing algorithm for recent HIV seroconversion (STARHS). CDC has applied this technology to develop the first national surveillance system of its kind that is based on direct measurement of new HIV infections. This system provides more precise estimates of HIV incidence (the annual number of new infections) than ever before, because it can more accurately distinguish recent from long-standing HIV infections.

Since CDC applied this advanced technology, the first estimates issued in August 2008 indicated that approximately 56,300 new HIV infections occurred in the United States in 2006. This figure is roughly 40% higher than CDC’s former estimate of 40,000 infections per year, which was based on limited data and less precise methods. A CDC historical trend analysis, also published in 2008, suggests that the number of new infections was likely never as low as the previous estimate of 40,000 and has been roughly stable overall since the late 1990s. The new estimate does not represent an actual increase in the number of new infections, but rather reflects the ability to more precisely measure new HIV infections. Accurate measurement of new HIV infections assists CDC’s efforts in educating people about emerging health threats.

The results also confirm that the impact of HIV remains greatest among gay and bisexual men of all races, as well as among African American men and women. In 2006, infection rates among African Americans were seven times as high as Caucasians and almost three times as high as Hispanics, a group that was also disproportionately affected.

This innovative laboratory test will help CDC track the estimated number of new HIV infections in the United States annually. Information gathered from both the surveillance system and the test will allow CDC to better monitor the current course of the epidemic, target prevention efforts where they are needed, and assess the impact of current prevention efforts.

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