The present invention provides methods for preventing, treating, or reducing the severity of infection, including bacterial, viral, and fungal infections, and including infections of more complex etiology. The invention involves the administration of an alpha thymosin peptide regimen, so as to prime or enhance a patient's immune response for pathogen exposure. In certain embodiments, the alpha thymosin regimen is scheduled or timed with respect to potential or expected pathogen exposures. The regimen of alpha thymosin peptide as described herein provides the patient with a more robust immune response to pathogen exposure, including higher antibody titers and/or a more rapid antibody response. In certain embodiments, the patient is immunodeficient or immunecompromised, and/or the patient is hospitalized or scheduled for hospitalization, such that the regimen of alpha thymosin peptide helps to protect the patient from, or reduce the severity of nosocomial infection or illness.
