Characteristics of the Exposure Source and Risk of Human Immunodeficiency Virus (HIV) Transmission

HIV Infection Status of Exposure SourceRisk of HIV Transmission
Not HIV infectedNo risk
 Known not to be infected with HIV*
HIV status unknown/unknown sourceUnquantified
 HIV infection status unknown, HIV risk status unknown
HIV status unknown: low riskLow
 HIV infection status unknown, but known not to have risk factors
HIV status unknown: high riskIntermediate
 HIV infection status unknown but known to have 1 or more risk factors
HIV infectedHigh
 Known to be infected with HIV
  • * HIV infection is documented by presence of specific antibody to HIV in persons older than 18 months and by positive plasma HIV RNA polymerase chain reaction (PCR) assay results, positive cell-associated HIV DNA PCR assay results, or detection of plasma HIV p24 antigen in persons of any age.

  • Risk factors for HIV infection include male homosexual activity, injection drug use, blood transfusion or blood product infusion before 1985, or sexual activity with a member of a high-risk group. Some persons who have sex with members of a high-risk group do not identify themselves as at risk, because they are unaware of the risk history of their sexual partner. Their risk of HIV infection is related to the prevalence of HIV infection in their immediate community.

  • Absence of HIV infection is identified by laboratory documentation of negative HIV antibody or negative HIV DNA PCR assay results from a specimen collected close to the time of the exposure and in the absence of interval high-risk behavior or symptoms compatible with acute retroviral infection syndrome.