Rabies immunoglobulin is a vaccine that is able to provide passive immunity to rabies viral infection. The two types of rabies immunoglobulin vaccines are human rabies immunoglobulin or HRIG and purified equine rabies immunoglobulin or ERIG. The former, HRIG is created from the plasma of humans who are immunized with rabies vaccine and is the preferred form of rabies vaccine. It is usually given as an injection in the muscles.