How Long Does It Take for HIV to Show Up on a Test?

Antibody Testing

The time between the date of infection and when a test will produce a positive result is called the "window period." The testing method is one of the factors in determining what an individuals window period may be. The Human Immunodeficiency Virus is detected one of two ways. It can be detected by testing blood, an oral sample or urine for the antibody that is produced by the body once the HIV virus has been introduced into the system. The other method used is testing the blood for the actual HIV virus via RNA testing. The method of testing will determine how quickly a positive result may be obtained. When a sample is tested for the antibody, it can take up to two to 12 weeks from the time of infection for a result to come back positive. According to the Centers for Disease Control, the average time for an infected individual to have enough detectable antibodies in their system is 25 days. The CDC also reports 97 percent of infected people will produce a positive result within 3 months. In some rare cases, it may take up to six months for an individual to produce enough antibodies to be detected.

RNA Testing

When testing a sample for the actual virus through RNA, positive results are reached more quickly than with the antibody testing method. The RNA test has a much shorter window period. The CDC reports that the virus becomes measurable in the body of an infected person between nine and 11 days after infection. While RNA tests are able to detect the virus quicker than the antibody test, RNA tests are costlier and not as easily accessible as the antibody tests.

Other Factors

It is reported by the King County Health Department, Washington, that there is a false positive rate among testers using both antibody tests and RNA tests of between 2.6 to 5 percent. It is general practice to have a follow-up test completed 3 to 6 months after the initial test to make sure a false negative or false positive was not obtained. There are many myths regarding the ability of certain conditions and substances producing either false positive or false negative results in HIV testing. Alcohol, drug use or other diseases have no effect on HIV testing. According to the CDC, the sensitivity rate for all rapid result HIV tests are 99 percent or greater. With any test, there is a window for false results in rare cases. It is standard protocol to have repeated testing completed as soon as three months after initial testing for a confirmation of the result.