TABLE 3.

Type of Exposure and Risk of HIV Transmission per Exposure Event When the Source is HIV Infected

Type of HIV ExposureRisk of Transmission per Exposure Event
Blood transfusion170.95
Perinatal exposure18,190.13 to 0.45
Needle sharing (injection drug use)270.0067
Unprotected receptive anal intercourse5,29,31330.005 to 0.032
Needlestick (health care professional)4,25,260.0032
Unprotected receptive vaginal intercourse29,300.0001 to 0.003
Unprotected insertive vaginal intercourse29,300.0003 to 0.0009
Ingestion of human milk2023*0.00001 to 0.00004
  • * See text for derivation of per-event risk calculation.

  • Receptive anal intercourse and receptive vaginal intercourse refer to the risk of HIV acquisition for the person whose anus or vagina was entered by the penis of the exposure source.

  • Insertive vaginal intercourse refers to the risk of HIV acquisition for the person whose penis was inserted into the vagina of the exposure source.