Infants with initially negative virologic tests should be re-tested at age 1–2 months. With increasing use of ZDV to reduce perinatal transmission, most HIV-exposed neonates will receive 6 weeks of ARV chemoprophylaxis. Although prophylactic ARV therapy theoretically could affect the predictive value of HIV virologic testing in neonates, ZDV monotherapy did not delay the detection of HIV by culture in infants in PACTG protocol 076 and has not decreased the sensitivity and predictive values of many virologic assays [4,20-22, 28]. Whether the current, more intensive combination ARV regimens women may receive during pregnancy for treatment of their own HIV infection will affect diagnostic test sensitivity in their infants is unknown. Similarly, if more complex regimens are administered to HIV-exposed infants for perinatal prophylaxis, the sensitivity of diagnostic assays will need to be re-examined.
HIV-exposed children who have had repeatedly negative virologic assays at birth and at age 1–2 months should be retested at age 3–6 months. HIV infection can be reasonably excluded in non-breastfed infants with two or more negative virologic tests performed at age >1 month, with one of those being performed at age > 4 months [15].
Two or more negative HIV immunoglobulin G (IgG) antibody tests performed at age >6 months with an interval of at least 1 month between the tests also can be used to reasonably exclude HIV infection in HIV-exposed children with no clinical or virologic laboratory evidence of HIV infection. If there has not been previous confirmation of two negative antibody tests by 12 months, serology is recommended to confirm that maternal HIV antibodies transferred to the infant in utero have disappeared.
If the child is still antibody-positive at 12 months, then testing should be repeated between 15–18 months [29]. Loss of HIV antibody in a child with previously negative HIV DNA PCR tests definitively confirms that the child is HIV uninfected.
A positive HIV antibody test at >18 months of age indicates HIV infection [10].