Chemoprophylaxis and Immunoprophylaxis as Tools to Prevent Sexually Transmitted Infections/Human Immunodeficiency Virus

Sexually transmitted infections (STIs) remain a pressing global health challenge, with over one million new infections reported daily. In India, where centralised data are limited, an estimated 6% of adults acquire STIs annually, with syphilis being the most common. Beyond immediate illness, untreated STIs can lead to infertility, neonatal complications, cancers and immense psychosocial stress. Traditional approaches such as early detection, treatment and condom promotion have had limited success, particularly against asymptomatic infections and in populations facing stigma or barriers to healthcare. Shifts in sexual behaviour, including increased oral and anal intercourse, use of sex toys and reliance on emergency contraception, have contributed to rising STIs worldwide. In high-income countries, especially among men who have sex with men, decreasing condom use alongside access to human immunodeficiency virus antiretroviral therapy and pre-exposure prophylaxis (PrEP) has further driven this surge. These realities highlight the urgent need for preventive strategies beyond conventional methods. Prophylaxis of STIs is the prevention of the disease before it sets in. It can be achieved by various methods such as chemoprophylaxis or immunoprophylaxis for various sexually transmitted diseases. Chemoprophylaxis through PrEP, post-exposure prophylaxis, continued prophylaxis, periodic presumptive treatment and expedited partner therapy are proving to be highly effective. Meanwhile, immunoprophylaxis, particularly human papillomavirus and hepatitis B vaccination, has proven highly effective in reducing transmission and carcinoma risk. While prophylaxis is cost-effective and prevents disability-adjusted life years lost, challenges remain. These include adherence, drug resistance and the ‘risk compensation’ effect where perceived protection leads to riskier sexual behaviour. The way forward lies in scaling up accessible, stigma-free prevention services, ensuring country-specific clinical trials and closely monitoring antimicrobial resistance. Ultimately, a proactive, preventive approach can protect individuals and communities while reducing the long-term burden of STIs.