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Researched for a woman whose sex partner (a cad) of some four times
finally
told her he had herpes, and was on suppression.
Some of the sources are missing, and there is
NO guarantee about the statistics and statements below.
You're on your own.
Summary
The risk of catching herpes (genital/HSV-2) is much lower from
someone on herpes suppression than from some random person who just
doesn't think s/he has it.
Herpes (genital/HSV-2) is NOT easy to transmit while
dormant, and suppression keeps it dormant.
Transmission of herpes generally occurs during outbreaks and shedding,
when the virus is active.
For a scenario of a sexual fling, someone on suppression has a much
lower per-sex-act chance of transmitting herpes than would a partner
chosen randomly from persons claiming they don't have herpes.
For longer relationships, the relatively low per-act risk from
one on suppression mean the risk builds very slowly. Obviously,
the randomly chosen person may not have any cumulative risk,
but the other people in that group are much more likely to transmit
their infection, making the average risk of that group poor.
Things To Know
Herpes is transmitted skin-to-skin, not by male/female fluids.
And a lot of times it's skin in the pubic area, not the parts the
condom would be covering.
Ejaculate (and preseminal fluid) isn't a significant risk.
Slather away; fluid isn't generally a way to catch herpes; it's a skin thing.
Herpes suppression therapy is about as effective
as the Pill (in preventing what each is supposed to)
Chance of impregnation or herpes transmission based on sex frequency,
with the Pill and herpes suppression in use.
| Sex Frequency |
Chance per YEAR |
Of This Effect |
Notes |
|
typical
|
9%
|
Impregnated
|
9% is normal, but 0.3% for perfect use , q.v.
|
|
thrice weekly
|
7%
|
Transmitted
|
7 ±2% (5 to 9%)
|
|
once weekly
|
2.5%
|
Transmitted
|
2.5% ±0.5% (2 to 3%)
|
Perfect use of the pill means:
same time of day, no mistakes, no vomiting or diarrhea,
no antibiotics,
no drugs from a
certain list, no St John's Wort. alcohol doesn't matter unless it
makes you miss or delay a pill, etc.
If you're on the Pill having sex a few times a week for a year with someone
on suppression,
you're less likely to catch herpes than you are to get pregnant,
unless your use of the Pill is "perfect".
Herpes suppression is better than condoms at preventing transmission.
One study found how unprotective condoms actually are:
-
For herpes, condoms provide little to NO protection to men
-
For herpes, condoms provide MINIMAL protection to women
While you can use condoms in combination with suppression, the
suppression is already doing a huge amount of good, and condoms
have little to contribute.
Many STD clinics don't test for herpes.
It's too expensive, too many people already have it to bother, etc.
It still lets a person claim to have been tested for
everything they test for without finding out (or telling you)
about herpes.
A herpes blood test at a doctor's is needed to know.
There's a nearly 18% chance of someone having HSV-2 if they've
had lots of sex with even only 2 to 4 people who weren't
themselves virgins. And there's an 80% chance the person doesn't
know, and an 80% chance that the partner who gave it to them doesn't either.
You can't trust anyone's impression they're herpes-free without a blood test.
Note that this doesn't take into account false negatives/positives for
these tests.
The lowest risk person to have sex with may not be who you'd expect.
Here's the list from safest
first to riskiest last:
| Risk Per Sex Act |
|
Risk Per
100 Acts |
Acts For
10% Risk |
| percent |
fraction |
Group |
Herpes status and other details |
| 0% |
- |
Blood Tested |
A person found negative by blood test
(assuming no false negatives). |
0% |
∞ |
| 0%+ |
(low) |
Virgins |
Some get infected through nonsexual contact, often by oral/HSV-1 |
(low) |
(lots) |
| 0.06% |
1 in 1666 |
Suppressors |
Those on suppression therapy. Be sure they're taking it daily. |
5.8% |
175 |
| 0.4% |
1 in 250 |
Think Not |
Those who thinks they don't, aren't tested,
see no need to get tested, etc.
Around one in seven+ of them is wrong with a 1 in 30 transmit chance.
|
33.0% |
26 |
| 1.1% |
1 in 90 |
Careful |
Those who know they do, are NOT on suppression, and avoid sex
around times of prodrome, outbreak, stress, etc.
|
67.3% |
9 |
| 3% |
1 in 30 |
Careless |
Those who know they do, and ignore it entirely. |
96.6% |
3 |
So basically you're safer having a fling with a someone on suppression than
you are with most people (the Think Not, Careful, and Careless groups).
For long term relationships, get a
blood test (if you don't know) to see if caution will even matter.
...and remember that condoms you used only protected you a little.
...and any he used with other woman barely protected him at all.
To be fair, starting a long term relationship has different statistical
dynamics. Supposing you're a woman for a moment:
Over, say, a ten-year sexual relationship, the odds are that
you'll catch whatever he has. At that point, if you chose a random man
from the men who don't think they have HSV-2, he had a
20%+ chance of having it (substantially more for the hispanic and black
social - not genetic - groups)
combined with the 20%+ chance that you had it already
(e.g. for women with 2-4 sex partners ever)
and just gave it
to him. This basically means that long term couples
of Think Not people have 36%+ chance of both having herpes
(60%+ if they both had 5+ partners, etc), though with a good chance of
having noticed if one caught it from the other.
However, becoming an Think Not
carrier yourself isn't much of a life impact if you're asymptomatic.
Futher, taking a tablet a day for suppression might just pair with taking
daily vitamins anyway, and your health insurance might cover it 100%.
You can estimate your safety factor with math.
If you're planning on N sexual acts with someone with HSV-2
on suppression, you can compute the overall safety factor by
taking the chance of being safe once, such as 1665/1666, 249/250,
89/90, or 29/30, and multiplying N copies of the dividend together.
Subtract the safety factor from 1.0 to get the risk factor.
| safety | = (1665/1666)N |
| risk | = 1 - (1665/1666)N |
Example safety (still clear ratio) for once weekly sex acts for a year with someone on suppression:
| safety | = (1665/1666)52 |
| = 0.969… |
| = 96.9 % chance to still be clear |
Example risk from having sex three times per day for a year (1095 times) with someone on suppression
| risk | = 1 - (1665/1666)1095 |
| = 0.4818… |
| = 48 % chance of transmission |
To figure out how many times you can have sex together and stay at or
below a given risk factor - as in your prospective partner isn't
willing to take more than a 10% risk, and you want to see how many
times that translates to - convert the risk percentage a safety ratio,
then take the log (in base per-act-safety) of that safety ratio.
| acts | = logper_act_safety(safety) |
Examples for 10% risk (= 90% safety) for Careless and Suppressor groups:
| acts | = log29/30(0.9) |
| = 3.1 acts with a careless person = 10% risk |
| acts | = log1665/1666(0.9) |
| = 175.5 acts with a suppressor = 10% risk |
(What the .1 and .5 might be is left as an exercise for the reader.)
Sources (partial):
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Planned Parenthood:
http://advocatesaz.org/2013/09/30/std-awareness-how-can-i-protect-myself-if-my-partner-has-herpes/
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National Center for Biotechnology Information (government site):
http://www.ncbi.nlm.nih.gov/books/NBK47447/
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