Do condoms protect against all STIs?

No. Used correctly every time, condoms greatly reduce the risk of HIV and infections spread through fluids, like chlamydia and gonorrhea. They offer less protection against infections spread by skin-to-skin contact, such as herpes, HPV and syphilis, because those can affect skin the condom doesn't cover. Combining condoms with regular testing and vaccines like the HPV vaccine gives you broader protection.