It is thought that the risk of HIV transmission from a percutaneous injury is approximately 1 in 3000-- this number aggregates injuries of varying severity, including minor to severe exposures.
Factors associated with increased risk include the type of injury- deeper injury or hollow bore needles are worse; solid needles or minor lacerations less risk. Similarly, if the source patient had AIDS or a high viral load, the risk of transmission is likely to be higher.
Post-exposure prophylaxis should be considered in this circumstance; PEP is most effective within the first 1-2 days of exposure (I advocate starting PEP as soon as possible, preferably within hours). -BY
