New surveillance data from the U.S. Centers for Disease Control and Prevention (CDC) suggest that approximately one in 10 individuals diagnosed with HIV in recent years was infected with HIV strains resistant to at least one available antiretroviral.  The report, presented today at the 14th Conference on Retroviruses and Opportunistic Infections, mirrors other recent drug-resistant HIV transmission studies.

Bonus Coverage: AIDSmeds founder Peter Staley recently interviewed Dr. Calvin Cohen, research director of the Community Research Initiative of New England. Double click below to hear more about the CDC’s new data showing a rise of HIV drug resistance in the newly infected.

To hear the full interview click here.
The U.S. Variant, Atypical, and Resistant HIV Surveillance (VARHS) system, in which HIV specimens from newly diagnosed individuals are tested for drug-resistance mutations, was established by the CDC to provide the clearest picture to date of the scope and type of resistance in the U.S.

The analysis reported at CROI included 3,130 individuals from 409 sites in 11 states who were diagnosed with HIV between January 2003 and October 2006.  The system utilizes standard genotypic resistance testing, which identifies specific viral mutations associated with drug resistance.  Because these individuals had not yet started treatment, the presence of any HIV drug resistance mutations in their blood would indicate that the resistant virus was transmitted to them at the time of their infection.

Overall, 10.4% of individuals had evidence of resistance to at least one drug. Levels of resistance varied by drug class: resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) was most prevalent (6.9%), followed by nucleoside reverse transcriptase inhibitors (NRTIs) (3.6%), and protease inhibitors (PIs) (2.4%).

Only a small minority of individuals newly diagnosed with HIV (1.9%) had evidence of multiple-drug resistance (resistance to at least one drug in more than one class).  Of these individuals, 1.4% had resistance to drugs in two classes and 0.5% to drugs in all three classes.

Previous studies have suggested an increase in HIV drug resistance over time – from below 5% in the mid-1990s to more than 10% in recent years. Although the level of resistance seen in this analysis is roughly comparable to that of prior research, the CDC investigators cautioned that the new data cannot be directly compared to past studies because of differences in the populations studied and methodology.

The investigators noted that the transmission of HIV drug resistance has been a growing concern for many years, as greater numbers of HIV-positive individuals are taking antiretroviral drugs for an increased amount of time.  The possibility of infection with strains of HIV that are more difficult to treat underscores the importance of HIV prevention efforts and the continued need to identify more effective treatment strategies.  To help guide these efforts, the CDC plans to utilize the VARHS system to monitor trends in resistance over time.


Wheeler W, Mahle K, Bodnar U, et al. Antiretroviral drug-resistance mutations and subtypes in drug-naïve persons newly diagnosed with HIV-1 infection, United States, march 2003 to October 2006 [Abstract 648]. 14th Conference on Retroviruses and Opportunistic Infections, Los Angeles, 2007.