HIV Infection is Best Prevented by External Latex Condoms
External latex condoms, when used correctly and consistently, provide the strongest protection against HIV infection compared to other sexually transmitted infections. Multiple cohort studies, including those of serodiscordant couples (where one partner is HIV-positive and the other is HIV-negative), have consistently demonstrated a strong protective effect specifically against HIV transmission 1.
Why HIV Prevention is Superior with Condoms
The evidence base for condom effectiveness against HIV is uniquely robust:
- HIV transmission occurs through mucosal surfaces, and condoms provide an impermeable barrier to HIV and other viruses in genital secretions 2
- Consistent condom use reduces HIV transmission by 90-95%, meaning consistent users are 10-20 times less likely to become infected when exposed compared to non-users 3
- Laboratory studies confirm that latex condoms are impermeable to even the smallest viruses, including HIV 2
Comparative Effectiveness Against Other STIs
While condoms protect against multiple STIs, the protection varies by transmission mechanism:
- Infections transmitted between mucosal surfaces (like HIV, gonorrhea, chlamydia) are more effectively prevented than those transmitted by skin-to-skin contact 1
- Skin-to-skin transmitted infections (such as herpes simplex virus, human papillomavirus, syphilis) may have reduced protection if the infectious area is not covered by the condom 1
- Non-viral STIs (chlamydia, gonorrhea, trichomonas) show 59% reduction in acquisition with correct and consistent use, which is lower than HIV protection 4
Critical Success Factors
The distinction between "consistent use" and "correct use" is essential:
- Condom failure typically results from incorrect or inconsistent use rather than breakage (breakage rates are ≤2 per 100 condoms) 1
- Correct use requires: applying before any genital contact, using water-based lubricants only (oil-based products weaken latex), withdrawing while erect, and using a new condom for each act 1, 5
Clinical Implications
When counseling patients about STI prevention:
- Emphasize HIV as the primary infection for which condoms provide the most robust protection based on the strongest evidence 1, 5
- Acknowledge limitations for skin-to-skin transmitted infections while still recommending consistent use 1
- Focus education on both consistency and correct technique, as both are required for maximum effectiveness 4