Figure 2.

HIV-1 IgG level, days since infection, and window period

NOTE: The serologic testing algorithm for recent HIV seroconversion is based on a transient state in the HIV immunologic response among people with early HIV infection. Soon after infection, the HIV-IgG to non-HIV IgG ratio will be in a transient state (the window period) but will eventually stabilize. According to HIV subtypes B, E, and D- (BED) based empirical studies, the length of the window period might vary from person to person, but has been calculated to have a mean of 153 days since infection. The 153-day cutoff has an optical density value of 0.8 in the BED assay. Information derived from: Hendriks JC, Satten GA, van Ameijden EJ, van Druten HA, Coutinho RA, van Griensven GJ. The incubation period to AIDS in injecting drug users estimated from prevalent cohort data, accounting for death prior to an AIDS diagnosis. AIDS 1998;12:1537-44; and Taylor MM, Hawkins K, Gonzalez A, Buchacz K, Aynalem G, Smith LV, et al. Use of the serologic testing algorithm for recent HIV seroconversion (STARHS) to identify recently acquired HIV infections in men with early syphilis in Los Angeles County. J Acquir Immune Defic Syndr 2005;38:505-8.

HIV = human immunodeficiency virus

IgG = immunoglobulin-G