Increased awareness of HIV status prevented an estimated 6,000 new infections in the U.S. between 2002 and 2004, according to a report in this month’s Journal of Acquired Immune Deficiency Syndromes. This is, of course, very good news – and is one indication of the value of HIV testing and prevention efforts. To put this number in perspective, I’ll briefly summarize the study and what I think are some of its most important points.
To estimate the number of prevented infections, the researchers relied on information from the Centers for Disease Control and Prevention (CDC). According to CDC, the proportion of HIV-infected persons in the U.S. who were aware of their HIV status increased from about 70.5% in 2001 to 74.2% in 2004.
This increased awareness of HIV status is important, because HIV-infected persons who are aware of their status are more likely to take steps to prevent transmission than HIV-infected persons who are unaware of their status. In addition, when HIV-infected persons know their status, they can seek the medical care needed to maintain or improve their health and quality of life.
Another important number that the researchers used for their calculation was CDC’s estimate of the number of new HIV infections per year. That estimate is 40,000 infections per year – or a total of 120,000 infections between 2002 and 2004. (It’s worth noting here that CDC is expected to issue a revised – and many expect higher – estimate of new infections in the near future.)
Using a mathematical model, the researchers then calculated the number of new infections that were prevented by increased awareness of HIV status. They came up with a best estimate of about 6,000 prevented infections – although the actual number might be as low as 4,000 or as high as 8,700. They also calculated that these prevented infections would save more than $5 billion by avoiding HIV-related medical costs and allowing people to continue working.
These are impressive benefits from a relatively small (3.7%) increase in awareness of HIV status. Unfortunately, the reason for this increased awareness is not known. The researchers speculated, however, that “Overall increases in testing rates and increased use of testing services by at-risk subgroups may have contributed to the reported increase.” They also noted that “other prevention initiatives likely helped as well” in preventing a rise in new HIV infections, despite the fact that the total number of people living with HIV increased by about 90,000 between 2002 and 2004.
At the end of their paper, the researchers make several insightful comments. They write: “One can argue that the incidence of HIV in the United States remains unacceptably high and that this indicates a failure of HIV prevention.” They then acknowledge that the first assertion – that infection rates remain unacceptably high – may be true. But they note that the second assertion – that HIV prevention has failed – goes against the facts. According to their calculations, if there had been no change in awareness of HIV status, the number of new infections per year would have risen from 40,000 in 2001 to more than 43,000 in 2004.
They conclude: “Although additional prevention activities are needed to reduce HIV incidence to lower than current levels, the success of past prevention efforts should not be overlooked.”
