Herpes is transmitted via skin-to-skin contact, not through blood or saliva. Cullins explains that someone with HSV can be shedding the herpes virus without having an outbreak (known as asymptomatic virus shedding), and infect somebody that way. Suppressive antiviral medications, like acyclovir or valacyclovir, inhibit HSV replication, which decreases shedding but does not completely eliminate it, says Johnston.
As of 2017, there is not currently a herpes vaccine available to prevent HSV-1 or HSV-2. (There is a vaccine available for another virus, herpes zoster; however, despite the similar name, it actually refers to the shingles virus. And, in fact, shingles occurs due to the reactivation of yet another virus, varicella zoster, which causes chicken pox.)
If you think you have or have been exposed to herpes you should see your primary care provider for follow up, screening, and possible treatment. Many providers today will not test unless you have symptoms of an outbreak, as often tests come back as false positive and the CDC has concluded that false positives cause psychological trauma to those tested. There is much debate on if you should test without symptoms or not, others say it is unethical to not be aware of your current STD status and risk infecting other people.