Can you provide per-act transmission risk estimates (%) for HSV-1 & HSV-2 for:

1. Oral Sex-unprotected, giving/recieving

2. Vaginal Sex: unprotected, condoms, w/antivirals, both combined.

Please include male to female vs female to male differences and assumptions. (Asymptomatic shedding vs outbreak).

If per-act oral data is limited, what are the best estimates or relative risk comparisons? 

1.  We have no data at all on oral sex transmission but the general risk would be someone with oral HSV 1 giving oral sex to someone who does not have HSV 1.

The estimate of risk of transmission are based on multiple studies - some show higher risk than others, for sure - based on about twice a week intercourse with no symptoms present.  Male to female transmission- in a year about 10% of females will become infected with no interventions.  Condoms used with every encounter reduce the risk by about 96%, daily antivirals by 48%.  Disclosure also reduces transmission by about 50%.  Female to male transmission - about 4 men out of 100 will acquire infection given the same circumstances with no interventions.  Again, antivirals reduced by 48%, disclosure by about 50%, and condoms by 65%.

Clearly, the risk of transmission goes down the longer couples are together.  

Terri

Condoms reduce by 96% to .4%

Antivirals reduce 48% to .2%

Female to Male 4%

Condoms reduce by 65% to 1.4%

Antivirals reduce by 48% to .728%

So under 1% per year with all precautions?

In the past questions, you responded to an inquiry about how performing cunnilingus runs a low STI risk. You stated the risk of acquiring HSV 2 is low by performing cunnilingus, but not impossible. It has also been stated in other responses, that if the giver already has HSV 1, they would have protection against HSV 2.  

Is that correct? 

Yes, the risk of acquiring HSV 2 orally by giving oral sex to someone that has HSV 2 is low because HSV 2 has a strong site preference for the genitalia.  

And no, having HSV 1 does not protect against getting HSV 2 - not at all - but having HSV 2 first protects almost fully against the acquisition of HSV 1.

Terri