Condoms – 85% or 99% effective?
Everyone (and every website) is either claiming that condoms are 85% effective or 99% effective, depending on whether they are pro-abstinence or pro-condom use. Some people have tried to reconcile these 2 figures by saying that with correct use, the condom is 99% effective while with incorrect use, it is 85% effective.
But what do the figures really mean?
I did a bit of research, and came across this letter (see attached, ‘8th Dec’ ) published on 8th December 2004 in Today. (I’m not sure where he got his information from; I looked up the original NIH article, and attached it here too). Here is the most interesting bit:
That figure refers more accurately to risk reduction. The 2001 report by the United States’ National Institute for Health that Dr Hui quotes, states: “Among participants who reported always using condoms, the summary estimate of HIV/Aids incidence was 0.9 seroconversion (HIV-positive testing) per 100 person years. Among those who reported never using condoms, (it) was 6.7 seroconversions per 100 person years.”
Overall, it was estimated that “condoms provided an 85 per cent reduction in HIV/Aids transmission risk” when comparing “always” with “never” users of condoms.
What this means is, for every 100 couples (where one partner is HIV-positive) who have repeated sex over a year and who use condoms every time, only 0.9 persons will test positive. Or, if you consistently have sex using condoms with an HIV-positive person over a 100-year period, your chance of becoming HIV-positive after 100 years would be 0.9 per cent.
The 85-per-cent figure arrived at is because the risk of infection in having sex with an HIV-positive person without using a condom is not 100 per cent.
If it were, the figure would be 99.1 per cent.
I went looking through other research articles, and found that there are 2 main ways people calculate their “effectiveness” statistics.
The first way (and this is supposed to be the correct way, according to my professors at NUS) is the one shown above, where you ask, out of 100 condom users, how many get infected/ pregnant? Then you ask the same question of the non-condom users. Then you calculate the percentage difference and that’s the effectiveness. So even if 1/10,000 condom users got infected, but 8/10,000 non-condom users got infected, the effectiveness is still 80%. According to our local NUH study, only 1 of 2000 patients surveyed got an abortion due to condom failure.
So , 85% effectiveness does NOT mean that 8.5 out of 10 times you have sex with a condom, you’ll be protected, but 1.5 out of 10 times, your condom will fail you.
The second way, which is what condom companies like do, is to ask, out of 100 condoms, how many will burst when it shouldn’t? And the answer is usually much less than 1 out of 100 for the GOOD brands. So then you have 99% effectiveness!
What do all these mean for the USERS?
Firstly, condoms are still the ONLY way to protect yourself against STIs.
Abstinence is definitely great, but only if you choose to abstain your whole life long. The moment you decide to have sex (at 16, at 26, when you’re married, when you’re 46, whatever), condoms are your only protection against STIs. Be faithful? Remember, most female HIV patients in Singapore are faithful wives.
Secondly, if used INCORRECTLY, condoms are 0% effective – as good as not using.
Forget what people say about, with incorrect, inconsistent use, condoms are only 85% effective, rather than 99%.
Think about it, if your condom bursts, or you put it on too late, or it leaked, or it slipped off, or whatever happened, body fluids would have already been exchanged, which is exactly what would have happened if you did not use a condom.
However, even if you did not use a condom, it does not mean you DEFINITELY would get pregnant or get an STI. So when you look at those statistics, don’t think that just because not EVERYONE got pregnant or got an STI when they didn’t use condoms correctly it means there’s some protection. The message we need to stress is, Use a condom, and use it right!
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In 2004, I had the opportunity to rebutt. this was published in the today paper (possibly edited)
I refer to Dr Hui Keem Peng’s letter (Dec 4 2004 Today) Condom Myth is No tall Tale.
In the 2001 report by the United States’ National Institute for Health that Dr Hui mentioned, it is stated:
“Condom usage was classified into the following three categories: always (100% use), sometimes, and never. Among participants who reported always using condoms, the summary estimate of HIV/AIDS incidence from the twelve studies was 0.9 seroconversion per 100 person years. Among those who reported never using condoms, the summary estimate of HIV/AIDS incidence from the seven studies was 6.7 seroconversions per 100 person years. Overall, Davis and Weller estimated that condoms provided an 85% reduction in HIV/AIDS transmission risk when infection rates were compared in always versus never users.”
What this means is for every 100 couples (one of which is hiv+) having sex repeatedly through the course of a year, using condoms every time, only 0.9 persons sero-converted to HIV-positive.
This suggests that if you are HIV-negative, and with the consistent benefit of condoms, you had sex with an HIV-positive person over a 100-year period, your chance of being HIV-positive after 100 years would be 0.9%.
The 85% figure is arrived because the risk of HIV infection with a hiv+ person without benefit of condoms is not 100%.
If it were, the figure would be 99.1%.
Thus it can be clearly seen that anti choice radicals who consistently quote 85% figures are being scientifically illiterate or deceitful.
Yours Sincerely
Christopher Low
n.b.
(6.7 – 0.9)/6.7 * 100 = 85%
(100 – 0.9)/100 * 100 = 99.1%
*to clarify, an 85% risk reduction is not the same as saying something is 85% effective.
Hi Chris Low, Thanks so much for commenting and putting up your original article! It’s a real honour = )
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Hey Chris Low, thanks for the clear description. Really appreciated, you are 100% right saying *to clarify, an 85% risk reduction is not the same as saying something is 85% effective.
Merlin Beach