A Caution About Rapid HIV Testing

Now that an estimated 1 in 4 Americans with HIV is infected without knowing it, tests that provide rapid results have been welcomed with open arms. But imagine if you were told you're HIV positive and later learn that you actually don't have the virus. In New York City, some people have had that experience: One rapid test that examines oral fluid samples—the OraQuick Advance Rapid HIV-1/2 Antibody Test—has produced a higher than expected number of false positives, leading the city's Department of Health and Mental Hygiene to suspend use of the test in its STD clinics; the OraQuick finger prick test is still in use.

A woman uses the OraQuick rapid HIV testing device at the South Brooklyn Health Center in New York City.

Jennifer Ruth, a spokesperson at the Centers for Disease Control and Prevention, says the agency is investigating clusters of false positives associated with the oral test in other jurisdictions as well. The uptick in false positives was the subject of the CDC's June 18 Morbidity and Mortality Weekly Report. (OraSure Technologies, the maker of the oral test, says that while New York City data showed higher than expected rates of false positives, the nationwide data the company has gathered are reassuring.) The CDC has not yet determined the cause of the increase in false positive results but is planning a study in areas that perform large numbers of HIV tests and have experienced an increase in false positive results.

The CDC recommended in 2006 that all people ages 13 to 64 be routinely screened for HIV unless they opt out of the testing. You can contact your doctor to get tested or find the nearest HIV testing site by calling the CDC's confidential information line at (800) 232-4636 (or 888-232-6348 for TTY). Also, the CDC's online locator allows you to look for close testing sites and find locations that offer free testing.

Here's a summary of the options for those who are considering an HIV test, adapted from the CDC:

• A traditional blood test known as the EIA (enzyme immunoassay) is the most common screen for HIV, though getting the results back from the lab can take several days, or longer if you initially test positive. It, like most HIV tests, detects antibodies produced after the virus enters the body. Other types of EIA tests include oral fluid (in which a specimen is collected using a special device) and urine tests. Traditional and rapid blood and oral fluid tests are thought to have similar accuracy rates, the rise in recent false positives notwithstanding. But the urine test is less sensitive and accurate than blood and oral fluid tests.

• The CDC lists the six rapid HIV tests that have been approved by the Food and Drug Administration. These include oral fluid, finger prick, and blood tests. Test results come back in about 20 minutes. Positive results must be confirmed by another test, which may take a few days to a few weeks. Both the OraQuick oral fluid and finger prick tests are more than 99 percent accurate, according to the FDA.

• Just one home testing kit, the Home Access HIV-1 Test System, is approved by the FDA. The test is sold online for $44 for one test, or $77.95 for a pack of two tests. Users collect finger prick samples at home and send them to a laboratory for testing. Results are available in seven days, and the manufacturer claims nearly 100 percent accuracy.

• RNA tests cost more and are used less frequently. They look for actual DNA of the virus and may be used to screen blood supply or to look for very early infections, when the body has not yet produced detectable antibodies to the virus.