The CDC (Center for Disease Control and prevention)
recommends the following regarding the DUO (4th generation) HIV
test: “Laboratories should conduct initial testing for HIV with an FDA-approved
antigen/antibody combination (4th generation) immunoassay that detects HIV-1
and HIV-2 antibodies and HIV-1 p24 antigen to screen for established infection
with HIV-1 or HIV-2 and for acute HIV-1 infection. No further testing is
required for specimens that are nonreactive on the initial immunoassay.”
To better explain, the probability
of estimation of whether a sexual partner had HIV is 1 in 1,000. For
a single incidence of unprotected sex, we can estimate an average transmission
risk of 1 in 1,000. So even prior to testing, the odds you caught
HIV are in the range of 1 in a million. If you undergo a DUO test at
30 days post-exposure (about 4 weeks), and if we base our assumptions on the
fact that the DUO test is "only" 99% sensitive by that time, then the
negative result means the chance you are infected becomes 1 in 100 million,
i.e., almost nil. At 99.99%, it's 1 in 10 billion.
