Getting and keeping an undetectable viral load prevents HIV transmission during sex. But there are situations when either partner may want to use additional prevention options. Using condoms can help prevent some other STDs. Using condoms or having your partner take PrEP can provide added peace of mind. Also consider using additional prevention options if you Are unsure, for any reason, that you have an undetectable viral load; Have a high viral load (200 copies of HIV per milliliter of blood or greater); Have trouble taking HIV medicine regularly; Missed some doses since your last viral load test; or Have stopped taking HIV medicine or may do so in the future.