CDC Issues New Recommendations on HIV Testing To Speed Diagnosis

July 21, 2014

New recommendations for HIV testing in laboratories will lead to HIV diagnosis as much as 3 to 4 weeks sooner, according to the CDC.

New recommendations for HIV testing in laboratories will lead to HIV diagnosis as much as 3 to 4 weeks sooner, according to the CDC.

The new approach "capitalizes on the latest technology to improve diagnosis of acute infection, the earliest stage of HIV infection when people are most likely to transmit the virus," said Jonathan Mermin, MD, MPH, director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention. “Identifying acute infections has long been one of our nation's biggest HIV prevention challenges, since these infections eluded traditional testing technologies. But with consistent and widespread use of this new testing method, we can diagnose people several weeks earlier than before.”

Dr Mermin added that the CDC is supporting laboratories to adopt this new approach as quickly as possible.

The updated recommendations for HIV testing are necessary because improved HIV assays now allow detection of HIV sooner after infection than previous immunoassays. There is evidence that relying on Western blot or indirect immunofluorescence assay for confirmation of reactive initial immunoassay results can produce false-negative or indeterminate results early in the course of HIV infection, according to the CDC report. Also, the risk of HIV transmission from persons with acute and early infection is much higher than that from persons with established infection. Recent indications show clinical benefits from antiretroviral treatment of all persons with HIV infection, including those with acute infection. The majority of HIV-2 infections detected by available HIV antibody immunoassays are misclassified as HIV-1 by the HIV-1 Western blot.

Testing begins with a combination immunoassay that detects HIV-1 and HIV-2 antibodies and HIV-1 p24 antigen. All specimens reactive on this initial assay undergo supplemental testing with an immunoassay that differentiates HIV-1 from HIV-2 antibodies. Specimens that are reactive on the initial immunoassay and nonreactive or indeterminate on the antibody differentiation assay proceed to HIV-1 nucleic acid testing for resolution. The results of this algorithm may be used to identify persons likely to benefit from treatment, to reassure persons who are uninfected, and for reporting evidence of HIV infection to public health authorities, the CDC states.

“HIV testing is the linchpin for prevention and treatment. For people who test HIV-positive, diagnosis opens the door to life-saving treatment, which also reduces the risk of transmitting HIV to others. For those who test negative, knowing their status empowers them to remain HIV-free,” said Dr Mermin.

He noted that "nearly 1 in 6 people living with HIV in the United States do not know they have HIV, meaning that they are missing out on essential care and may unknowingly transmit the virus. Roughly half of the estimated 50,000 new HIV infections each year are transmitted by people who don't know that they are HIV-positive."

Dr Mermin added that the nation is making "steady progress" on HIV testing, and the new recommendations "could help the nation reduce that number further."

The CDC published its report "Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations" on June 27, 2014.