When testing is indicated, it should be done following institutional and state-specific exposure-control policies and informed consent guidelines. In all situations, the decision to begin antiviral PEP should be carefully considered, weighing benefits of PEP versus the risks and toxicity of treatment.
Human immunodeficiency virus. If a source patient is known to be HIV-positive, has a positive rapid HIV test, or if HIV status cannot be quickly determined, PEP is indicated. Healthcare providers should be aware of rare cases in which the source patient initially tested HIV-seronegative but was subsequently found to have primary HIV infection.
Per 2004 CDC recommendations, PEP is indicated for all healthcare workers who sustain a percuanteous injury from a known HIV-positive source.3,8 For a less severe injury (e.g. solid needle or superficial injury), PEP with either a basic two-drug or three-drug regimen is indicated, depending on the source patient’s viral load.3,5,6,8
If the source patient has unknown HIV status, two-drug PEP is indicated based on the source patient’s HIV risk factors. In such patients, rapid HIV testing also is indicated to aid in determining the need for PEP. When the source HIV status is unknown, PEP is indicated in settings where exposure to HIV-infected persons is likely.
If PEP is indicated, it should be started as quickly as possible. The 2005 U.S. Public Health Service Recommendations for PEP recommend initiating two nucleosides for low-risk exposures and two nucleosides plus a boosted protease inhibitor for high-risk exposures.
Examples of commonly used dual nucleoside regimens are Zidovudine plus Lamivudine (coformulated as Combivir) or Tenofovir plus Emtricitabine (coformulated as Truvada). Current recommendations indicate that PEP should be continued for four weeks, with concurrent clinical and laboratory evaluation for drug toxicity.
Hepatitis B virus. Numerous prospective studies have evaluated the post-exposure effectiveness of HBIG. When administered within 24 hours of exposure, HBIG might offer immediate passive protection against HBV infection. Additionally, if initiated within one week of percutaneous injury with a known HBV-positive source, multiple doses of HGIB provide an estimated 75% protection from transmission.
Although the combination of HBIG and the hepatitis vaccine B series has not been evaluated as PEP in the occupational setting, evidence in the perinatal setting suggests this regimen is more effective than HBIG alone.3,6,8
Hepatitis C virus. No PEP exists for HCV, and current recommendations for post-exposure management focus on early identification and treatment of chronic disease. There are insufficient data for a treatment recommendation for patients with acute HCV infection with no evidence of disease; the appropriate dosing of such a regimen is unknown. Further, evidence suggests that treatment started early in the course of chronic infection could be just as effective and might eliminate the need to treat persons whose infection will spontaneously resolve.7