Routine serologic screening of patients at risk for HIV-1 or HIV-2 infection usually begins with a HIV-1/-2 antigen and/or antibody screening test, Antibodies against HIV-1 and HIV-2 are usually not detectable until 6 to 12 weeks following exposure and are almost always detectable by 12 months.However with the addition of p24 Antigen the HIV status can be determined between 11th day to one month after getting infected with HIV. HIV virus causes Acquired Immunodeficiency Syndrome (AIDS). As per NACO guidelines, all reactive samples are tested by three different methods prior to release of report.