Post-exposure prophylaxis (PEP) is defined as taking antimicrobial medication after being exposed or potentially exposed to an infectious agent to prevent becoming infected.PEP is routinely used for prevention of a variety of viral, bacterial, and parasitic infections, including influenza and human immunodeficiency virus. Based on experience with PEP for other infections, therapy should be started as soon as possible after a recent possible exposure.
Hydroxychloroquine (HCQ) is currently approved for the suppressive treatment and treatment of acute attacks of malaria due to several Plasmodium strains. It is also indicated for the treatment of discoid and systemic lupus erythematosus and rheumatoid arthritis. With the first Food and Drug Administration approval in 1955, safety and tolerability of HCQ are well described.
In vitro, HCQ displays antiviral activity against coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pharmacologic modeling based on observed drug concentrations and in vitro drug testing suggest that prophylaxis at approved doses could prevent SARS-CoV-2 infection and/or ameliorate viral shedding. Clinical trials of HCQ treatment for coronavirus disease (COVID‑19) pneumonia are underway in China under separate protocol(s).