Chemoprophylaxis

Chemoprophylaxis is the administration of a chemical agent to prevent infection in people exposed or at risk of infection. It is used ahead of exposure (pre-exposure prophylaxis, PrEP) or after exposure (post-exposure prophylaxis, PEP), and is part of infectious disease prevention alongside vaccination and other public health measures. It aims to reduce incidence and transmission by suppressing or interrupting pathogen replication during the window of vulnerability.

Applications include malaria chemoprophylaxis for travelers and residents in endemic areas; antimicrobial prophylaxis around surgical procedures or in patients with prolonged neutropenia; antiviral prophylaxis in immunocompromised individuals or after known exposure to herpesviruses; and HIV PrEP using combination antiretroviral therapy. Prophylaxis may also be used in outbreak settings, for example meningococcal exposure.

Drug selection depends on the likely pathogen, resistance patterns, pharmacokinetics, comorbidities, and adherence considerations. Regimens vary widely and are tailored by guidelines and clinicians. Adverse effects, drug interactions, and contraindications must be weighed against the risk of infection. Widespread use can drive antimicrobial resistance, reduce drug efficacy, or cause toxicity, highlighting the need for surveillance and stewardship.

Chemoprophylaxis is not a substitute for vaccination when vaccines are available, nor a cure for established infection. It is one component of a broader prevention strategy, including vector control, safe practices, and prompt treatment of breakthrough infections.