Laboratory definitive evidence of HIV infection in an individual aged 18 months or older requires:

• A repeatedly reactive result on an initial antigen/antibody combination immunoassay that detects HIV-1 and HIV-2 antibodies or HIV-1 p24 antigen AND a reactive result on an HIV-1/HIV-2 antibody differentiation immunoassay OR
• A repeatedly reactive result on an initial antigen/antibody combination immunoassay that detects HIV-1 and HIV-2 antibodies or HIV-1 p24 antigen AND a reactive result on the HIV-1 nucleic acid test (NAAT) test.

Laboratory definitive evidence of HIV infection in an individual aged under 18 months requires:

• A repeatedly reactive result on nucleic acid test (NAAT) test on specimens taken at two different dates.