Condom effectivness

[fixarn2008]

Hello, this is the second time I write to you and really want to thank you for your splendid answer to my last question. I had a discussion with some of my friends about a condoms effectivness in protecting against STD's.
Since we couldn't agree we started to search the net and found numerous sites giving varying information. Some calimed it offered good protection but not total protection, some only said it offered good protection and som said it wasn't a protection you can count on etc.
I'm from sweden so I have looked at both swedish and english sites (the swedish are often govermental and claims good, but not 100% protection, the english is more varying)
So heres my question:
How good protection does a condom really offer in a single encounter for the different STD's assuming the partner really has the STD in question? For example, HPV, HSV and Syphilis is claimed to  be possible to transmit despite the use of condom since it could be an lesion outside the area protected by the condom.
Can you give some figures (if there is any to give) for:
1. Gonorea
2. Chlamydia
3. HSV-2 (and 1 if relevant)
4. Syphilis
5. HIV
7. HPV
8. Trichomonas (ok, I know it is rare but it was in my list)

If it is possible, please give figures with and without condom, vaginal, oral and petting.

[Edward W Hook, MD]

Welcome back to the Forum.  The questions you ask suggest that you are hoping for a level of precision that simply is not available.  For starters however, remember that most exposures to partners with STDs do not lead to transmission of infection.  Thus, in a statistical sense, since most people do not have STDs and most exposures do not lead to transmission of infection, STD transmission from any single exposure is a rather rare event.  In some instances the studies have not been performed, in others the methods used in the studies are questionable.  Please also remember that to study condom effectiveness, scientists need to rely of study subject self report, something that may be unreliable and subject to bias.  Furthermore, the data a also confounded by problems such as occasional condom breakage (occurs about 1% of the time) and the entire issue of whether or not the condom is being used properly, something that doesn't always happen either.  So, with those limitations, here are some or the current estimates of how much condoms reduce risk for some of the STDs you ask about, based on not a single but evaluation of multiple studies:

HIV:  proper condom use reduces risk of HIV transmission by over 99%
Gonorrhea and chlamydia:  Condoms reduce risk of transmission by over 90%
Syphilis:  The data are less precise and highly variable but syphilis transmission is reduced at least 80%

Herpes.  condom use reduces transmission by about 60%
HPV.  Very hard to say but condoms appear to reduce transmission by over 60%
Trichomonas.  there is no available information.

Again please remember that these are estimates and subject to limitations. The bottom line is that all well done studies indicate that condoms do SIGNIFICANTLY reduce risk for STD transmission and are to be encouraged.  After all, releatively rare or not, when STDs can be avoided, they should be and most peole who have and transmit STDs do not know it

Hope these comments are helpful to you.  EWH

[fixarn2008]

So, at the bottom line:
If used properly and no breakage it would be unlikely (but not impossible) to find someone to have sex with that is infected, who is contagious at the moment (if this differs over time as with, in some respect, HSV, HPV and syphilis) and still be infected inspite correct use of condom (through the entire intercourse) that does not break.

Thank you for a very good answer.