Final answer:
It is true that one should avoid all sexual contact until tested, as this is a key method for preventing STIs. Condoms significantly reduce, but do not completely prevent, the risk of STI transmission. Two STIs that often have mild or no symptoms are chlamydia and HPV.
Step-by-step explanation:
The statement 'avoid all sexual contact until you have been tested' is indeed true. When it comes to preventing STIs (Sexually Transmitted Infections), abstaining from sexual activity or having only one uninfected faithful partner is the only certain way to avoid infection. Two STIs that often go unnoticed because they commonly do not cause symptoms, or cause only very mild symptoms, are chlamydia and human papillomavirus (HPV).
Regarding the use of condoms, it is important to note that while proper use of condoms can greatly reduce the risk of transmission of STIs, it cannot completely prevent it. This is because STIs can be present on areas of the body not covered by condoms, and there is also the possibility of condoms breaking or being used incorrectly. Additionally, antibiotics cannot be used to treat viral STIs such as genital herpes, and while they are used for bacterial infections like chlamydia, they do not address the viral aspects of some STIs.