Sexually transmitted infections (STIs) are infections passed on to others through unprotected sexual contact (sex without a condom). Every year, 640,000 cases of STIs are diagnosed in England, including chlamydia, for which 70% of women and 50% of men carrying the infection will not show any symptoms.

Although there are treatments for chlamydia and genital herpes, it is important to always use a condom during sex to prevent STIs and unwanted pregnancies.