New HIV Test Cuts 'Window Period'
FDA Approves Test That Detects HIV Sooner After Infection
June 21, 2010 -- The FDA has approved the first HIV test to detect the AIDS virus itself as well as antibodies to the virus.
Most currently used HIV tests detect anti-HIV antibodies. But it takes two to eight weeks -- 25 days on average -- for a person newly infected with HIV to make detectable antibodies. Meanwhile, that person is highly infectious to others.
The new test, from Abbott, still doesn't work immediately after infection. But it cuts the crucial window period between infection and detection by "at least a week, and it could be as much as 20 days," Abbott senior director Gerald Schochetman, PhD, tells WebMD.
The weeks soon after a person contracts HIV are the acute phase of HIV infection. This is when the virus replicates wildly, before the immune system kicks in to slow it down. A person is highly infectious during this time -- but may still test negative for HIV on tests that look only for anti-HIV antibodies.
"The most sensitive third-generation antibody tests will pick up about 42% of acute-phase infections, whereas the new combination assay picks up about 90% of those in the acute phase," Schochetman says. "It is a substantial increase over current tests."
Abbott's new test already is approved in Europe. The U.K. and France use the test as their primary HIV screening test.
The Abbott combination test isn't the first test to detect HIV itself. But the nucleic acid tests capable of early detection are too expensive to use for first-line HIV screening.
HIV testing is the cornerstone of the U.S. effort to reduce HIV infections. Data show that people who know they are infected with HIV are far less likely than those who don't know their HIV status to transmit the infection to others.
Pictorial Timeline of the HIV/AIDS Pandemic