Pre-exposure prophylaxis (PrEP) is the use ofmedications to prevent thespread of disease in people who have not yet been exposed to a disease-causing agent.Vaccination is the most commonly used form of pre-exposureprophylaxis; other forms of pre-exposure prophylaxis generally involve drug treatment, known aschemoprophylaxis. Examples include taking medication to prevent infection bymalaria orHIV. In particular, the termPrEP is now synonymous in popular usage with the use ofpre-exposure prophylaxis for HIV prevention.
In general, the use of pre-exposure prophylaxis requires balancing the risks of the treatment (e.g.,side effects from a drug) to healthy individuals with the risk of the disease.
It is contrasted withpost-exposure prophylaxis (PEP), which is used once the patient has already been exposed to the infectious agent.
The use of pre-exposure drug treatment to preventmalaria usingantimalarial drugs is well-established,[1] with the use ofquinine as a prophylactic treatment dating back at least to the 19th century.[citation needed]
The abbreviationPrEP now often refers topre-exposure prophylaxis for HIV prevention, the use ofantiviral drugs as a strategy for theprevention of HIV/AIDS.[2] PrEP is one of a number ofHIV prevention strategies for people who are HIV-negative but who have a higher risk of acquiring HIV, including sexually active adults at increased risk of contracting HIV, people who engage in intravenous drug use (seedrug injection), and HIV-negative members ofserodiscordant sexually active couples.[3]
When used as directed, PrEP has been shown to be highly effective at preventing HIV infection, reducing the risk of acquiring HIV by up to 99%.[4] A large-scale study in the UK has shown that PrEP remains effective at preventing HIV infection, even when used in uncontrolled environments.[5]
Pre-exposure prophylaxis against infection bySARS-CoV-2, the virus that causesCOVID-19, has been studied as a possible preventive measure for high-risk groups.[6]
In December 2021, the US FDA granted emergency use authorization (EUA) of the antibody drugtixagevimab/cilgavimab (Evusheld) to prevent COVID-19 in immunocompromised people who cannot be fully vaccinated due to a history of a severe reaction to coronavirus vaccines.[7][8] However, due to the high levels of non-susceptible SARS-CoV-2 variants present in the US, the FDA announced on 6 January 2023 that tixagevimab/cilgavimab was no longer currently authorized for emergency use in the US.[9]
In March 2024,pemivibart (Pemgarda), amonoclonal antibody drug, received an emergency use authorization from the US FDA to protect certain moderately to severely immunocompromised individuals against COVID-19.[10][11]
Pre-exposure prophylaxis against infection by therabies virus, the virus that causesrabies, is recommended for high-risk individuals such as veterinarians, travelers to rabies-endemic areas, and individuals from rabies-endemic areas (especially children and people from rural areas where rabiespost-exposure prophylaxis might not be readily accessible).[12][13]
The standard dosage for rabies pre-exposure prophylaxis is two 1ml doses of therabies vaccine (HDCV, PCEC, or PVRV) administered intramuscularly (IM) on Days 0 and 7. The vaccines used for rabies pre-exposure prophylaxis are the same ones used for post-exposure prophylaxis.[14][15]
Since conducting autopsies may involve inadvertent cuts, and the incidence of hepatitis-B can be very high in certain populations, it is advisable for all autopsy personnel to get their hepatitis-B antibody status tested. If antibodies are not present in sufficient concentrations, a hepatitis-B vaccine is recommended.[16]