The human immunodeficiency virus (HIV) changes (mutates) often. Sometimes these changes make the virus resistant to a particular medicine or class of medicines, which means the medicine is no longer effective against the virus. When this happens, the medicine no longer controls virus growth (replication) or protects the immune system.
Resistance testing is done to determine whether resistance has caused treatment to fail and to identify antiretroviral medicines that can be used to treat the infection. There are many reasons that treatment fails, such as:
About 40 million people are living with HIV (human immunodeficiency virus) or AIDS (acquired immunodeficiency syndrome). Each day, 14,000 more become infected. HIV drugs have vastly improved the quality of life for many of these people, but they don't yet provide a cure. That's why researchers are working so hard to develop an HIVvaccine.