For genital herpes, condoms are highly effective in limiting transmission of herpes simplex infection.The virus cannot pass through latex, but a condom’s effectiveness is somewhat limited on a public healthscale by their limited use in the community, and on an individual scale because the condom may not completely cover blisters on the penis of an infected male, or the base of the penis or testicles not covered by the condom may come into contact with free virus in vaginal fluid of an infected female. In such cases, abstinence from sexual activity or washing of the genitals after sex is recommended. The use of condoms or dental dams also limits the transmission of herpes from the genitals of one partner to the mouth of the other (or vice versa) during oral sex. When one partner has a herpes simplex infection and the other does not, the use of antiviral medication, such as valaciclovir, in conjunction with a condom, further decreases the chances of transmission to the uninfected partner. Topical microbicides which contain chemicals that directly inactivate the virus and block viral entry are currently being investigated. Vaccines for HSV are currently undergoing trials. Once developed, they may be used to help with prevention or minimize initial infections as well as treatment for existing infections.
As with almost all sexually transmitted infections, women are more susceptible to acquiring genital HSV-2 than men. On an annual basis, without the use of antivirals or condoms, the transmission risk of HSV-2 from infected male to female is approximately 8-10%. This is believed to be due to the increased exposure of mucosal tissue to potential infection sites. Transmission risk from infected female to male is approximately 4-5% annually. Suppressive antiviral therapy reduces these risks by 50%. Antivirals also help prevent the development of symptomatic HSV in infection scenarios—meaning the infected partner will be seropositive but symptom free—by about 50%. Condom use also reduces the transmission risk by 50%. Condom use is much more effective at preventing male to female transmission than vice-versa. The effects of combining antiviral and condom use is roughly additive, thus resulting in approximately a 75% combined reduction in annual transmission risk. These figures reflect experiences with subjects having frequently-recurring genital herpes (>6 recurrences per year). Subjects with low recurrence rates and those with no clinical manifestations were excluded from these studies.
The risk of transmission from mother to baby is highest if the mother becomes infected at around the time of delivery (transmission risk 30 to 60%), but the risk falls to 3% if it is a recurrent infection, and is less than 1% if there are no visible lesions. To prevent neonatal infections, seronegative women are recommended to avoid unprotected oral-genital contact with an HSV-1 seropositive partner and conventional sex with a partner having a genital infection during the last trimester of pregnancy. A seronegative mother that contracts HSV at this time has up to a 57% chance of conveying the infection to her baby during childbirth, since insufficient time will have occurred for the generation and transfer of protective maternal antibodies before the birth of the child, whereas a woman seropositive for both HSV-1 and HSV-2 has around a 1-3% chance of transmitting infection to her infant. HSV-1 being transmitted by oral sex as HSV-2 is not very common but there is always the risk  Women that are seropositive for only one type of HSV are only half as likely to transmit HSV as infected seronegative mothers. Mothers infected with HSV are advised to avoid procedures that would cause trauma to the infant during birth (e.g., fetal scalp electrodes, forceps, and vacuum extractors) and, should lesions be present, to elect caesarean section to reduce exposure of the child to infected secretions in the birth canal. The use of antiviral treatments, such as aciclovir, given from the 36th week of pregnancy limits HSV recurrence and shedding during childbirth, thereby reducing the need for caesarean section.