How well condoms actually work is a tricky question

Since the advent of PrEP (pre-exposure to HIV prophylaxis), some sources have maintained that condoms are highly effective and better to use than PrEP.

In fact, condoms may not be as effective as they are touted to be. But not for the reasons critics might argue. In order for condoms to be effective, you have to use them, and use them correctly.

Before I delve into all of this, let’s take a step back and explain what PrEP is.

Here’s the CDC’s description:

Pre-exposure prophylaxis, or PrEP, is a way for people who do not have HIV but who are at substantial risk of getting it to prevent HIV infection by taking a pill every day. The pill (brand name Truvada) contains two medicines (tenofovir and emtricitabine) that are used in combination with other medicines to treat HIV. When someone is exposed to HIV through sex or injection drug use, these medicines can work to keep the virus from establishing a permanent infection.

When taken consistently, PrEP has been shown to reduce the risk of HIV infection in people who are at high risk by up to 92%. PrEP is much less effective if it is not taken consistently.

PrEP is a powerful HIV prevention tool and can be combined with condoms and other prevention methods to provide even greater protection than when used alone. But people who use PrEP must commit to taking the drug every day and seeing their health care provider for follow-up every 3 months.

Bacon condoms, seriously. And if you use their bacon-flavored lubricant, it even tastes like bacon.

Bacon condoms, seriously. And if you use their bacon-flavored lubricant, it even tastes like bacon.

Now, back to the debate as to whether condoms are more effect than PrEP at preventing HIV infection. This really gets into a much larger discussion, which I have below, about just how effective condoms actually are. And it’s more complicated than people might realize.

How well condoms work depends on a number of factors. It might be a good idea to review some information on condoms, since many people may be unaware of some important points concerning condoms and their proper use. Even if you think you’re quite familiar with correct condom use, some of this information may be new to you.

How to use condoms correctly

1. To successfully prevent infection with most sexually transmitted infections, condoms must be used with each sexual contact.

2. Have extra condoms available in case one is damaged, tears, etc.

3. Apply the condom before ANY sexual contact begins.

4. Apply it to the erect penis unrolling it along the length of the penis. Squeeze out any excess air.

5. Most condoms are made from latex. Others are made from polyurethane (a type of plastic.) Some, the “natural” condoms, are made from animal material. The latter can allow viruses like HIV and HPV to cross through the condom. To prevent this, latex condoms should be used.

6. Latex condoms should only be used with water-based lubricants. Oil-based lubricants, products like Crisco, Vaseline (petroleum jelly) and others, can significantly weaken the latex.

7. Use plenty of water-based lubricant.

8. Older condoms are less effective in preventing sexually transmitted infections (STIs). They can begin to deteriorate over time. And certainly don’t use condoms that are older than their “sell by” date or expiration date.

9. Keeping a condom under unfavorable conditions (excessive heat, cold, pressure, etc.) can damage it and cause it to lose effectiveness. So leaving condoms in a glove compartment in a car, in a wallet where it is crushed under a person’s body weight or subjecting it to other physical trauma, may make it much less effective.

10. The condom can only protect what it covers. Make sure that it is unrolled completely. Even with a fully unrolled condom, some STIs can be transmitted by contact by other body parts: kissing, anilingus, fellatio and others.

11. The condom should be inspected before use to make sure that there are no obvious holes, tears or other physical damage. Condoms are often put on very hurriedly, under conditions of low light. Sometimes the user is under the influence of drugs, alcohol or both. The latex is thin and can rip with rough handling. Some people tear open the condom wrapper with their teeth and the condom can be damaged by that process. All of this can add up to damage to the condom itself, and thus a decrease in its efficacy.

12. After climax, pull out immediately holding the base of the condom to prevent its slipping off. Look at it for any obvious tears.

13. After use, the condom should be removed correctly and disposed of properly. Improper removal or disposal can cause contamination of the hands or other body parts with the very secretions and STIs that the condom is used to prevent.

14. Wash hands after removing the condom.

15. Never reuse a condom.

You can go here for additional information on condoms and correct use.

Now, how effective are condoms?

How effective are condoms? That varies due to a number of factors. Some are described above. If the condom isn’t used correctly, is damaged, tears during sex, the protection afforded is very low.

But if condoms are used correctly, how effective are they?

If we just look at data that is concerned with condom use to prevent STIs (and not focus on condom use to prevent pregnancy) the data shows a fairly wide range of efficacy. The reasons for that include the following.

Much of the data is based on self-reporting from volunteers in the studies. So the accuracy of that information depends on how truthful the subjects in the study are. One study showed that men who reported that they used condoms might only use them about 60% of the time. Another study that quizzed men who reported using condoms found that, at times, they may have used condoms incorrectly >40% of the time. So the data from similar studies may differ solely because of the accuracy of the people involved in the study.

Another point that can add to different efficacy rates is that many of the parameters in various studies differ. Some studies are done using male-female couples having penile-vaginal intercourse only. Others are done on man who have sex with men (MSMs) who have penile-rectal intercourse. Other studies include both groups. A few look at how much knowledge the couples have about condom use; many don’t look at that at all. A few studies looked at serodiscordant (one member HIV positive, one HIV negative) couples. Some look at only how well condoms protect against just HPV or just syphilis or just hepatitis. Others looked at how well condoms protect against viral STIs but not STIs caused by other organisms. Therefore, the data can be bewildering unless the methods of the individual study are reviewed as well as the numbers.

Because of the above, and a few other reasons, some the information that I present below is drawn from the World Health Organization (WHO), National Institutes of Health and the United Nations, which looked at large number of condom studies. In additions, there are also some individual studies with interesting and somewhat unsettling information included.

First, let’s look at condoms to stop the heterosexual transmission of HIV

In heterosexual serodiscordant couples:

Consistent condom use (i.e., using condoms during every act of vaginal intercourse) among heterosexual couples in which one partner was infected with HIV reduced the risk of HIV transmission from men to women and vice versa. This finding was based on a meta-analysis of condom effectiveness studies by Davis & Weller (2). They estimated that compared with no condom use, consistent condom use resulted in an overall 87% reduction in risk of HIV transmission, with the best-case and worst-case scenarios ranging from 60% to 96%. In an update of this analysis, Weller & Davis reported a revised estimate of an 80% reduction in risk with a range of 35–94%.

So consistent condom use did reduce HIV transmission, but only between about 80% to 87%. And the reduction in risk could be as low as 35-60%.

A word about efficacy vs. relative risk reduction. Relative risk reduction is reduction in the absolute risk based on some intervention (e.g., using condoms), expressed as a percentage of the whole exposed group before the intervention.

But efficacy is the extent to which something is effective in meeting its objectives under ideal conditions. Ideally, the intervention would be 100% effective.

Condom use among MSM/gay men

The fastest-growing subset of HIV cases in the US is found in young MSMs (teens through twenties), especially in African-Americans. How well do condoms protect them?

The data from Alberta reported by Genuis (massive promotion of condoms followed by upsurges in gonorrhoea and chlamydia) are mirrored in Spain. Spain, together with Greece, stands out as the European country with the highest levels of condom use among young people, with 90% of sexually active young people reporting using a condom the last time they had sexual intercourse. Nevertheless, the rates of sexually transmitted infections (STIs) are increasing year after year, despite more than a decade of intensive official educational campaigns transmitting the message to young people that condoms and only condoms are the magic bullets to prevent all STIs and unintended pregnancies.

Education about condoms and successful compliance with their use by young people is not decreasing STIs in these two countries. In fact, the reverse is true. As condom use increased, so did rates of transmission of STIs.

Condom use in adults and young adults.

Now, how about condom use in adults and young adults:

The main problem with condoms is that average people, particularly aroused youth, do not use them consistently, regardless of knowledge or education. Although condoms offer some protection against discharge related infections such as chlamydia and gonorrhoea, protection is usually compromised by compliance issues, incorrect use, or mechanical failure.

In theory, condoms offer some protection against sexually transmitted infection; practically, however, epidemiological research repeatedly shows that condom familiarity and risk awareness do not result in sustained safer sex choices in real life. Only a minority of people engaging in risky sexual behaviour use condoms consistently. A recent study found that less than 8% of couples discordant for herpes used condoms for each sex act, despite ongoing counselling. Even among stable, adult couples who were HIV discordant and received extensive ongoing counselling about HIV risk and condom use, only 48.4% used condoms consistently. Irregular use of condoms will not provide sustained protection against sexually transmitted infection.

The relentless rise of sexually transmitted infection in the face of unprecedented education about and promotion of condoms is testament to the lack of success of this approach. In numerous large studies, concerted efforts to promote use of condoms has consistently failed to control rates of sexually transmitted infection—even in countries with advanced sex education programmes such as Canada, Sweden, and Switzerland. In my home province of Alberta, rates of chlamydia and gonorrhoea have tripled since 1998 despite ubiquitous “safer sex” education. The ongoing assertion that condoms are “the” answer to this escalating pandemic reminds me of Einstein’s words, “The definition of insanity is doing the same thing over and over again and expecting different results.”

Reports of diminished rates of sexually transmitted infection as a result of widespread condom use in countries such as Thailand and Cambodia are reinforcing the focus on condoms as the primary strategy. Careful scrutiny of the data, however, suggests that changes in sexual behaviour (fewer partners, less casual sex, and less use of sex workers) after mass educational campaigns rather than widespread condom use by ordinary citizens was instrumental in reducing infection rates.

It appears that people don’t want to use condoms in spite of education. In fact, a few countries tried providing free condoms to their citizens. Briefly, the use of condoms skyrocketed. But in less than two years, the increase diminished to back to near baseline levels of use. The investigators inferred that perhaps condoms were a novelty or fad and once that wore off, people were no longer interested in using them.

So, technically, this isn’t the failure of condoms themselves to prevent STIs, it’s the failure of people to use them (or to use them correctly.)

In a study done for the United Nations on reduction of HIV transmission done on heterosexuals, gays and bisexuals:

According to a meta-analysis commissioned by UNAIDS, condom use is 90% effective in preventing transmission, and condom use has been a key element in reductions in HIV prevalence in many countries. [AUTHOR’S NOTE: This meta-analysis and the data upon which it was based were done years before PrEP was available as a possible alternative. That is, no head-to-head study of PrEP v. condoms could be done at that time.]
[. . . ]
But, where the epidemic is largely heterosexual and widespread, evidence on the effectiveness of condom programs has been more mixed and less clear. In Uganda, while it is clear that condoms have played a role in lowering infection rates, reducing the number of sex partners appears to have played at least as large a role. In other words, condoms should not be seen as distinct from other strategies but as an integral part of comprehensive strategies that also counsel abstinence and reducing the number of sexual partners.

Interestingly, another similar study, not a meta-analysis, done in 2005, showed that HIV rates were successfully reduced by 82% by condom use. Again, this study used gays, bisexuals and heterosexuals as subjects.

So, where does this leave us? How effective are condoms in preventing STIs?

Condoms do provide protection from infection with STIs.

As described above, it is difficult to show the exact efficacy because of the factors previously described (correct use of the condom, methodology of the studies, etc.) It seems that much of the data shows that, with correct and at least very frequent use, condoms may be able to decrease transmission of STIs by somewhere around 80-90% depending on the physical characteristics of the STI in question.

Can condoms help to protect against getting an STI like HIV? Yes, if they are used and used correctly.

Are they being used frequently and correctly? No.

Are they the best defense against acquiring an HIV infection? No. Condoms should be seen as a part of prevention of STIs, specifically HIV, not as the only method to prevent it.

If condoms are effective and people are aware of this, why aren’t more people using condoms? Much like the discussion on the effectiveness of condoms, there are a number of reasons why they’re not used.

Availability is one. Depending on the location, in developing countries, for example, condoms may not be readily available.

Emotional factors can also play a role in whether condoms are used. Some reports that are taken from interviews with study volunteers say that sometimes the partner objects to using a condom. The partner claims that the potential condom-wearer is doubting the sexual health of the other partner. Sometimes the partner of the condom-wearer, when seeing the condom, fears that his/her partner has an STI and refuses to have sex. Some people are embarrassed to purchase or use condoms, especially teens.

Other factors may include: cost of the condoms, poor planning on the part of the participants, allergy to latex, decreased sensation that may be caused by condom use, decreased spontaneity, an unplanned sexual encounter, loss of erection while placing a condom, “condom fatigue” (people become tired of using condoms and following other safer-sex suggestions in general and a variety of others.

One or more of these can be enough to cause the couple to not use a condom. If the condom isn’t used, the efficacy falls to zero. Only about 65% of American males use condoms consistently (note that “consistently” does not equate with using a condom for every sexual contact.) The Centers for Disease control estimates that about 20% of sexually active MSMs do not use condoms at all or use them only sporadically.

There are methods that can be used to increase the use of condoms and they help somewhat. Some examples are:

  • Make using a condom part of foreplay.
  • Explore using different colors and textures.
  • Sometimes having a condom education event where both partners and singles are taught about condom use will increase the use of condoms after the event.
  • People who meet online should discuss STI status before meeting in person.
  • Explaining that using condoms along with PrEP can significantly decrease the chance of contracting HIV.

To sum up, condoms can help protect against HIV and other STIs if used properly and consistently.

The exact efficacy of how well condoms prevent HIV and STIs varies based on a variety of factors. At times, it may be very low, at other times quite high. Data compiled by health organizations shows that condom use can decrease the rate of HIV transmission by somewhere between 80-90%.

Making condoms available and having people use them does not always decrease STIs.

Education about STIs and condoms does help increase their use, but not dramatically and not long-term.

There are methods that can help people to become more accepting of condom use and these should be encouraged.

Condoms alone are not sufficient to eliminate the spread of HIV. They need to be used in conjunction with other techniques and behaviors.

Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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