The CDC has estimated the following probabilities of infection following ONE exposure to HIV:
Contaminated blood transfusion (prior to 1986) 95%
HIV infection rate:
One intravenous syringe or needle exposure 0.67%
One percutaneous exposure (e.g. a needlestick) 0.4%
One episode of receptive anal sexual intercourse 0.1%-3%
One episode of receptive vaginal intercourse 0.1%-0.2%
One episode of insertive vaginal intercourse 0.03-.09%
A 1% risk means 1 chance in 100 for infection to occur. A 0.10% risk means 1 chance in 1,000. There are no published estimates of the risk for transmission from receptive oral sex or insertive anal sex.
Infection
