A reader in Hanoi asks why sexually transmitted infections (STIs) can still occur even with consistent condom use. While condoms are highly effective in preventing STIs, they are not foolproof. Several factors contribute to this, including improper use, condom breakage, or STIs transmitted through skin-to-skin contact not covered by a condom. Some infections, like herpes or HPV, can be spread through areas not fully protected by a condom. It's crucial to use condoms correctly and consistently, but regular STI testing and open communication with partners remain essential components of sexual health. Relying solely on condoms isn’t a guarantee against all STIs.