Fourth-Generation HIV Tests Can Reduce Transmission Over Time

It's no secret that treatment for HIV/AIDS has improved over the years, and PLWHA are living longer and healthier lives. But treatment isn't the only weapon in the fight against HIV/AIDS that has gotten better with time. HIV testing has also improved dramatically, with the current generation of HIV tests helping to identify the presence of the disease sooner and, by doing so, reducing the transmission of HIV.

Fourth-generation HIV tests are the latest crop of screening tools for the disease. Earlier-generation HIV tests worked by identifying HIV antibodies—proteins produced by the immune system when it detects HIV—in the bloodstream. Fourth-generation tests, on the other hand, work by not only detecting HIV antibodies but also detecting p24 antigen, a protein that is found in the virus itself.

"The reason why this is so important is that when people first get infected with HIV, it takes a few weeks for the body to develop an immune response to it," says Joanne Stekler, M.D., M.P.H., associate professor in the Division of Infectious Diseases at the University of Washington's Harborview Medical Center in Seattle. As a result, with fourth-generation HIV tests, an HIV diagnosis can be made sooner after infection than was previously possible.

Anyone who has ever feared being exposed to HIV understands how reassuring it can be to be able to find out your status weeks rather than months after exposure. The earliest HIV tests had window periods—the time between infection and detection by an HIV test—of six weeks to three months, Dr. Stekler says. Third-generation tests can detect infection on average about three to four weeks after exposure. Fourth-generation tests can detect the presence of HIV as early as two to two-and-a-half weeks after infection, Stekler says.

The Benefits of Earlier Detection

There are a number of pluses to getting an earlier HIV/AIDS diagnosis. A person who knows his or her status can:

* Start treatment sooner. The sooner treatment begins, the better the outcome and the more likely a person with HIV will live a longer and healthier life.

* Make informed behavioral changes, such as using condoms and urging sexual partners to get tested, which can cut down on the transmission of HIV/AIDS.

* Lower his or her viral load, which lowers the risk of HIV transmission sooner.

With earlier-generation tests, there was more of a risk that someone would fall through the cracks because an HIV test did not detect a recent infection.

"Someone may wrongly think, 'Oh, I'm fine, I can have sex without a condom with my partner,' and it's in this period of time that people's virus levels are really high and people are very infectious," Dr. Stekler says. "Our goal is to get people diagnosed as soon as possible after infection so that they can get into care and start taking HIV medicines, but also start making changes in their behavior to protect their partners."

Fourth-Generation Tests in the U.S.

The first fourth-generation HIV tests made available in the United States were approved in 2010 by the Food and Drug Administration. However, the U.S. lagged behind other nations, such as the United Kingdom and other European countries, which adapted to the tests earlier.

There are currently two laboratory-based fourth-generation tests available: Abbot Architect HIV Ag/Ab Combo assay and Bio-Rad GS HIV Combo Ag/Ab EIA. In 2013 the FDA approved the first fourth-generation rapid point-of-care HIV test: Alere Determine HIV-1/2 Ag/Ab Combo.
Although fourth-generation tests are available in the U.S., that doesn't mean you're guaranteed to get one if you get screened for HIV. Some organizations may offer third-generation tests because they are less expensive to administer or for other logistical reasons.

If you think you've been exposed to HIV and it's within the first 72 hours, go to an emergency room for postexposure prophylaxis—medications that can reduce your chances of becoming HIV positive.

If it is past that period of time, you want to get the most sensitive test possible. If someone offers fourth-generation testing, you can find out sooner whether you've been infected.

The broader impact of fourth-generation testing is that it will lead to earlier diagnoses and lower transmission of HIV. "It is critical to use a test with a shorter window period when you're talking about populations of people that have ongoing HIV transmission and you are likely to miss people who have been recently infected," Dr. Stekler says.

Tamara E. Holmes is a Washington, D.C.-based journalist who writes frequently about health, wealth and personal growth.