Condoms: The science

The Vatican has published a document which says condoms have holes in them, allowing HIV - the virus that causes AIDS - to pass through.

The document, called Family Values versus Safe Sex, is a detailed and passionately argued defence of the Church's position on condoms.

Its author, Cardinal Alfonso Lopez Trujillo, serves as the President of the Pontifical Council for the Family and is known for his hard line stance against contraception.

It goes so far as to suggest that condoms may even be one of the main reasons for the spread of HIV/AIDS.

The document claims that so-called safe sex using condoms is like playing "Russian Roulette."

"Leading people to think they are fully protected..." the document says, "is to lead many to their death."

Vatican opposition to birth control is a time-hallowed moral teaching, but in this document the Cardinal has called science to its aid. His document has 87 footnotes.

Panorama has investigated the topic to find the truth.

We have looked at many scientific papers - including all those cited by the Cardinal - and talked in depth with leading experts on AIDS and condoms. Our aim was to find the best scientific evidence about condoms and HIV.

Here are some highlights of our research. Click on the link to find the relevant section of read the whole piece from the top:

Comparison with sperm
Other sources cited by the Cardinal
Infectivity estimates
Scientific consensus
Nevada brothels
Slips and tears
Risk to the individual
Making things worse
Promiscuity and risk-taking behaviour
The conclusion

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Comparison with sperm

Cardinal Trujillo's comments that the HIV virus is much smaller than the sperm has been quoted around the world.

"The AIDS virus is roughly 450 times smaller than the sperm," he told Panorama last year. "So scientists realise that there is a degree of uncertainty. It might be 15%, 18%, or 20%."

In his paper, Cardinal Trujillo quotes Dave Lytle - who was a senior researcher at the US Food and Drug Administration in the 1980s and 90s.

Lytle led a team at the FDA which looked at the question of HIV and condoms in the 1980s.

Lytle's most conclusive work was conducted with actual viruses - but not HIV, that was too dangerous.

His team tested 470 condoms and found twelve of them "allowed some virus penetration."

In his document Cardinal Trujillo uses this statement to endorse his case that the AIDS virus HIV can pass through condoms.

"My reaction is one of disappointment," Dave Lytle told Panorama. "[Cardinal Trujillo] didn't pay attention to the paper, he took a number out of it, and basically misused it."

Lytle points to important differences between his laboratory test and real life. The viruses he used were a fifth size of HIV. Lytle used easy-flowing water - not as viscous as semen. The pressures he used to test condoms were higher.

And he'd tested the whole condom surface - any hole might have been in a different place to the semen.

Here is David Lytle's opinion of Cardinal Trujillo comparing the HIV virus to the sperm: "In terms of size, the comparison is correct," said David Lytle.

"In terms of the motility, no. You have to wait for either fluid flow or simple diffusion for the virus to go some place. And that's assuming that there's a hole in the condom that it can go through."

He concluded that only one condom out of all those he tested might conceivably leak any infectious HIV - and even if it did, the amount leaked would be minimal.

"If we translate that into real life circumstances the amount that went through the condom would be just barely visible if it were on a white surface," he told Panorama.

Lytle concluded that normal intact condoms are impermeable to HIV.

Dave Lytle's worst case condom

Lytle also says the worst case condom he found would have been a "water leaker."

Under international regulations imposed by bodies like the FDA in the USA and the WHO, batches of condoms have to be sampled by testers who inflate them with water and roll them over a blotter to see if there are damp spots that would indicate the presence of holes or ruptures.

Most international standards allow such condoms to pass through these "water leaker" quality tests with a permitted failure rate of 1 in 400.- though manufacturers we spoke to said they exceeded this quality rate, in the case of one famous brand name by a factor of ten.

There are other tests too - manufacturers use an electronic test of every individual condom which can show up any flaws.

But in Lytle's judgement even taking "water leakers" into account there is no risk to worry about.

"The latex condom is a very effective barrier," he said, "A few may allow minimal exposure to virus and if I were to give my children or grandchildren advice about whether to use condoms, I'd say absolutely."

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Other sources cited by the Cardinal

The Cardinal cites other sources for his claim that condom latex has holes which let HIV pass through and pose a serious health risk.

Panorama has checked all the sources cited by Cardinal Trujillo and we cannot substantiate his claims.

The world's leading experts on AIDS and condoms believe the findings and the conclusions of Lytle's work at the FDA. All the authoritative AIDS specialists cited by the Cardinal do in fact support the use of condoms against HIV.

We went through the main references cited by the Cardinal with Dr Lytle.

1. Dr Ronald Carey was the original head of the team at the US Food and Drug Administration which studied the permeability of latex condoms.

Dr Carey did a separate series of tests on latex condoms - the test was similar to Lytle's but used microscopic fluorescent beads instead of actual viruses.

In a seminar that Panorama has on video, Carey commented of Lytle's subsequent work that it was both more effective...and cheaper!

Lytle is a great admirer of the late Dr Carey but his own methods were more rigorous than those used by his mentor.

Cardinal Trujillo cites Carey's work to support his case that condoms are porous and can leak the HIV virus. In his document he says that Carey found 29 leaky condoms out of the 89 he tested. Lytle says he is "disappointed" by how Cardinal Trujillo cites his former colleague's work.

"He (Carey) decided that about one HIV virus could get through during the use of 200 condoms. And without condoms, the recipients would have been exposed to about 600,000 HIV viruses. The amount they found was very small, and when Ron tried to interpret this in terms of real risk, he decided it was about 10,000 times better than actually not having a condom at all."

Lytle's later decision to use actual viruses was taken because of uncertainty as to what was actually passing through in Carey's work, "whether it was actually the particle, or a dye coming off, or even some other source of fluorescence." He believed that using a virus - rather than fluorescent beads - would produce a much more accurate result.

2. An experiment to determine whether condoms leak HIV conducted at UCLA and referred to in an LA Times story quoted by Cardinal Trujillo. The Cardinal reports that four of America's most popular condom brands tested in this experiment 'permitted the AIDS virus to escape'. Lytle tried to reproduce the results in his own laboratory of a test that he says was an attempt to mechanically simulate the pressures from the sex act.

"When we tried in our laboratory to reproduce the process, the simulated sex act, we found we got shredded condoms. Now I think that doesn't happen in real life... I think what they did was they created holes in the condoms by the way they treated them, and then they said yeah, we have holes in the condoms."

"To my knowledge they didn't test any without having gone through this process of simulated sex act. I think subsequent tests were much more reliable."

Lytle does not of course mean that the UCLA team actually tested shredded condoms - simply that the pressures used on the condoms were extreme and that they were probably damaged

3. In 1989 Canada's R. Gordon argued that condoms "provide inadequate risk reduction for the individual" But Gordon - writing from the University of Manitoba's Department of Botany - also said that "if everyone used condoms, the AIDS epidemic would stop", since from a public health point of view they were effective enough increasingly to cut the number of cases.

On Gordon's 1989 work, et al in 1989, Lytle told us: "The data" was collected before 1989 and before that time the experiments were very poorly designed and executed with very few samples...I think subsequent experiments should take priority."

4. The work of Dr C M Roland - a leading specialist on rubber technology at the US Naval Research Laboratory - has been quoted by opponents of condoms although Cardinal Trujillo does not cite Dr. Roland directly. Dr Roland tested latex rubber film and wrote in 1998 that "small particles can pass through" but did not use actual viruses.

Dr C.M. Roland has also been quoted as being sceptical of the use of condoms against HIV. Panorama was told he was unavailable for interview. Lytle regards his work as "incomplete" compared to research at the Food and Drug Administration'[s labs. The 2000 Workshop on Scientific Effectiveness on Condoms did not list his research papers as being among those on which it decided to base its judgements.

Lytle comments: "He's actually, to my knowledge, only tested two samples of condoms, and what he did, he used fluorescent beads, similar to the ones Carey used, and we were concerned when we found out about it and we invited him up to talk to us."

"We went to see his lab and then later with one of the people who did that study in our lab we used viruses and the beads in the same experiment and found nothing of either to go through. We think the virus data should take precedence over the fluorescent bead data. What we know with virus is we don't get that kind of result."

Roland also refers to surgical latex gloves as being potentially permeable.

"The acceptable quality levels are different for condoms in gloves." Lytle told Panorama. "So it's possible he (Roland) found some holes. But the freeze fracturing method may cause artefacts and my impression from his writing is that this is a very common thing to see and in fact it's not common for viruses to go through the latex of gloves. And we've tested that extensively under much higher pressure and times than anything he's done. So I think again viruses don't seem to go through."

Dr Penny Hitchcock told Panorama that the latex gloves referred to by Roland would not have been made by double-dipping in latex, unlike modern condoms, "(so) it is likely that the hole is an artefact. If you were to use this method with a condom, you might be able to fracture between the 1st and 2nd layer, but you would need to lay the top and the bottom layers open and look for the hole in both layers in order to conjecture that the hole would leak fluid. Here is the catch: since the condom was double dipped after a 180 degree rotation, a hole that penetrated both layers would have to be the result of full thickness perforation AFTER it was made."

5. The Archbishop of Managua in Panorama's "Sex and the Holy City" argued that latex condoms must present a risk because he said that surgeons sometimes wear two layers of latex gloves. But according to Dr Lytle holes in gloves would be created during the surgery - "Surgeons abuse gloves where they do their work, on their fingertips, and they create breaks in the gloves. Really double gloving has to do with the damage they do to gloves in their work, has nothing to do with condoms."

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Infectivity estimates

Some scientists we spoke to believe that under normal circumstances - given the conservative nature of Lytle's assumptions - no HIV would pass through even Lytle's worst case condom in practice.

A paper released since Panorama interviewed Dr Lytle has suggested that for short periods of hyperinfectivity, abnormally high amounts of HIV may be present in semen.

So we asked Professor Pietro Vernazza, one of the authors of the paper, to help us understand the risk of coming across a condom like Lytle's worst case "water leaker" and being infected while using it.

Professor Vernazza put it this way: "We're talking about such miniscule risk that in general in our regular life is a zero risk."

"It's addition of several unlikely events - the unlikely (event) that the condom will have a tiny hole - the very unlikely event that a virus will pass thro that hole - and then even after that it's very unlikely that a virus that has passed will cause transmission."

"It happens as rarely as my plane crashes when I am on my vacation. Of course we take it into account that it could crash but we still go on vacation."

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Scientific consensus

The views of scientists like Lytle and Vernazza have been widely endorsed in the scientific community.

The World Health Organization describe any risk from intact condoms or water leakers as negligible - and they're not alone.

Dr Penny Hitchcock, was the Chief of the STD Branch in the US National Institute of Health from 1992 to 2001. Four years ago she chaired a conference of internationally recognized experts on condoms, STDs, HIV and bio-statistical evaluation of clinical studies - the US Condom Effectiveness Taskforce.

The deliberations of the taskforce are summarized in the 2000 Workshop Summary: "Scientific Evidence of Condom Effectiveness for Sexually Transmitted Disease (STD) Prevention".

Their report is the most authoritative to date.

"The data are consistent, there are no holes in condoms that present a risk of infection," Dr Hitchcock told Panorama.

"No one should not use a condom because they think it's going to leak," she said.

Scientists we spoke to dismissed any suggestion the risk rate from any permeability might be different in those regions of Africa where HIV prevalence in the general population is much higher.

Dr Hitchcock said, "I don't care whether they're in the United States or in Africa. They should be using condoms with confidence that if they use them correctly they'll prevent HIV infection."

"For the church to not support the use of condoms to prevent infection is very detrimental to our controlling the epidemic," she added.

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Nevada brothels

Panorama also visited what amounts to one of the best real-life laboratories available for estimating the effectiveness of condoms against HIV.

Brothels like Sheri's Ranch in Pahrump are legal in some counties in Nevada. The law says they must use condoms.

At Sheri's they reckon they use over 15,000 a year - for vaginal, oral and manual sex.

"They've done over 66,000 tests on ladies that worked in our brothel. There's never been one reported or documented case ever of any HIV," Laraine Harper, the Madame at Sheri's, told Panorama.

And it's not just Sheri's Ranch. Sixteen years ago Nevada started mandatory HIV tests for all legal sex workers.

There is no long-term follow-up. But according to state records no prostitute working in a legal Nevada brothel has ever tested positive for HIV.

Dr Steve Pinkerton is Professor of Behavioural Medicine at the Medical College of Wisconsin and has referred to the Nevada Brothels in his studies of HIV.

He told Panorama, "So far today there have been no documented cases of brothel workers in one of the legal Nevada brothels becoming infected with HIV."

"Brothel workers obviously have a lot of sex with a lot of sex partners, some of whom probably are infected with HIV. Yet none of those brothel workers have become infected. Why? Well for one reason they use condoms 100% of the time. It's state law."

"They follow it and they know how to use condoms correctly. There's a lot of evidence that suggests the people who use condoms often tend to use them correctly whereas the people who don't know how to use them tend to be those people who haven't used them regularly. Brothel workers know how to use condoms correctly, and so far the evidence would suggest that they've been protected in part because of that."

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Slips and tears

But the girls here are aware of a more real risk from condoms than holes -- that they may slip off or tear because they are not properly used. Jewellery or from rough sex for example, can cause problems.

But it's not something that concerns the sex workers here, because when it comes to using condoms they are professionals.

"I've been in the business a few years, on and off and I've used a lot [of condoms]. Thousands. It varies, there could be a week I use hundreds," Kayla, a sex worker, told Panorama.

The danger for everyone else is that the basic techniques of condom use are forgotten in the heat of the moment - or have never been learnt.

Sex worker Lara has good advice for proper condom use. "You keep a good grip on it," she told Panorama.

"You should actually at all times during intercourse keep your hand at the base of the penis holding the condom down, and then that way you can prevent [it slipping off]"

Another sex worker adds: "I don't let the gentleman touch them I just put them on because I know the correct way - and when you put them on you hold the tip of it and roll it down and make sure there's no air in it."

"We are extra careful," said Lara. "If we can safely depend on it to protect us, I should think someone in the general public would feel extraordinarily safe using the same type of protection."

"Obviously they have a lot of experience with a lot of different types of people, but there's no reason why the average person couldn't learn to use them half as well, or much better than they are," Dr Pinkerton told Panorama.

"There are a lot of very simple rules about condom use that people regularly don't follow and that leads to condom failure," he said. "For example not using a sharp object to open the condom wrapper, not unrolling it before putting it on the partner, or putting it on.

"There are a number of things that people do wrong that could easily be corrected. We don't all have to be experts like the brothel workers in Nevada."

It's worth noting the girls in Sheri's do not offer anal sex. Dr Hitchcock says, "We have effective tools to prevent HIV infection by every route of transmission (blood, dirty needles, perinatal, breast feeding and vaginal intercourse) - except for anal sex. We do not know how much protection is provided by the male latex condom" there were insufficient studies and published data for the Task Force to review. The main concern that could not be addressed was whether or not the slippage and breakage rates would be similar to those in vaginal intercourse. This does not mean that the latex condom does not provide protection - it means we don't have good evidence -- that the "jury is still out".

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Risk to the individual

So what risk to the individual is posed by condom use?

Penny Hitchcock, a strong supporter of using condoms against HIV, told Panorama, "When you consider what we know about the performance characteristics of available vaccines, diagnostic tests or drug therapy, the male latex condom rates among the best at doing 'its job'. It is one of the most effective tools available for prevention and control of a disease."

(The Vatican of course would say it's better not to take the risk of catching the disease in the first place and remain abstinent or faithful to an uninfected partner - though condom supporters point out many people often don't have the chance to know if their partner's infected).

The best figures we have for condom effectiveness in practice come from what's known as meta-analysis of different individual studies of sero-discordant couples.

Sero-discordant couples are those in which one person is HIV infected and the other isn't.

The meta-analyses are by Steve Pinkerton, and by Weller and Davis (the one quoted in the 2000 Workshop Summary).

One problem is that the length of studies are different. The Saracco study for example was conducted for 2 years. But Weller, Pinkerton and the WHO all agree the studies indicate that over a period of about a year about 99% of the uninfected partners of "always" condom users remained HIV negative.

Out of 867 sero-discordant couples not using condoms, Pinkerton found 171 HIV negative partners became infected. Of 277 couples saying they did use condoms consistently, there were 4 such infections.

Weller and Davis say "always" users became infected at the rate of 1.14 per 100 person-years, while "never" users became infected (or "sero-converted") at the rate of 5.75 per 100 person years.

Although the statistical practice is to give rates for one year, Dr Hitchcock told Panorama, "It is important to stress that each act of condom use is independent. In other words, the risk does not accumulate with each use of a condom. We have good evidence to suggest the opposite is true."

Dr Hitchcock explained, "There are three ways that prevention of HIV infection with use of condoms improves over time: 1) skills for putting the condom on correctly improve - "new" users of condoms will have a slippage and breakage rate of 10-15% per year whereas "practiced" users reduce that rate to 1%.

2) communication skills improve with practice - people get better at talking to their partners about condom use; 3) comfort with condom use increases and it becomes habitual - much like getting used to driving with a seat belt on."

Of course someone having sex with an HIV positive partner for 10 years with a condom will run a greater risk than if they only had sex in the same way for a year.

Some scientists and AIDS control agencies like to give a "risk reduction" figure - generally regarded as 80-90%.

We didn't use this figure on our programme because we think it can be - and has been - too easily misunderstood. Condoms are often described as being '80-90% effective - leading people to think that this means they fail 10% or 20% of the time.

A risk reduction estimate means that condoms can reduce your risk of becoming HIV positive - whatever that risk is - by 80-90%.

It is a figure derived from those 'sero-discordant' studies mentioned above by comparing how many uninfected people get the virus when they use always use condoms - with the number that get infected when they use them inconsistently or never use them at all.

In general what scientists find is that consistent use of condoms can reduce the risk of getting infected to between 10-20% of what it would be for people who never use them or who don't only use them regularly.

In all cases there is enormous protective advantage to using a condom compared to not using the condom - once a decision to have sex has been taken.

Dr Steve Pinkerton told Panorama, "A 10% failure rate doesn't mean the virus is going to be transmitted 10% of the time. Your partner might not be infected, or even if they are infected, the virus quite simply may not be transmitted.

"All it means is that 10% of the time there is a possibility of transmission. The other 90% of the time there is absolutely no possibility of transmission."

So - these figures show condoms offer substantial protection but are not perfect or foolproof.

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Making things worse

There's one other controversial point that is still worth investigating. Condoms, Cardinal Trujillo says, far from preventing the AIDS epidemic, may have actually made it worse.

Cardinal Trujillo says that safe sex campaigns which promote condoms lead people to think they're completely protected when they're not

"There is a good reason for a clear-cut prohibition against condoms," the Cardinal told Panorama last year, "far from stopping AIDS, they have encouraged promiscuity, leading many more people to get the disease."

As supporting evidence Cardinal Trujillo cites a paper by Professor Norman Hearst, Professor of Family Medicine and Epidemiology and the University of Califoirnia. He's studied AIDS across the world - including Uganda and Brazil.

Dr Hearst told Panorama that, contrary to the way Cardinal Trujillo has cited his research findings, there is no conclusive evidence that increased condom use leads to increased promiscuity.

But the Professor believes Cardinal Trujillo is right to question whether condoms are working against AIDS.

In some parts of the world, he says, they are not fulfilling the hopes so many have placed in them.

Hearst is one of a minority of experts who have begun to question the value of condom promotion in AIDS epidemics where the virus is being spread in the general population.

Other scientists who agree include Harvard's Edward Green, former WHO scientist Rand Stoneburner and his colleague Daniel Low-Beer of Cambridge University.

Their work is quite controversial and some of their most salient conclusions not generally accepted.

Hearst told us: "We know from our research that if you use condoms some of the time but not all of the time they do you little or no good."

"The concern is that we may have a generation of young people in at least some African countries growing up who have been taught to believe that condoms equal AIDS prevention and that believe they're doing their part by using condoms most of the time except when they don't happen to have one, or they happen to be drunk or they have a partner that they feel particularly attracted to or whatever."

"And that's just not going to do them much good."

"There may also be issues of the quality of the condoms may not be quite up to standards of what you or I would buy if we went to the pharmacy to get one, or the issues of storage and non-air-conditioned warehouses, there could be a lot of things but I think people need to be realistic in terms of what's really going to happen in Africa."

Dr Hitchcock however believes the lack of success for condoms in Africa is no reason to shift finance or promotion efforts to another agenda.

She said: "There may not be enough condoms to go around, or people are not using them, or people are using them incorrectly. The first is a supply issue. The other two are intervention issues."

Like other scientists and Cardinal Trujillo, Dr Hearst pointed to Uganda under President Museveni for an example of a different - and potentially more successful - method of reducing HIV rates.

Hearst said: "As President Museveni said in countries like ours where a woman has to walk 20 miles to get an aspirin for her sick child or five miles to get any water at all, the issue of a consistent supply of condoms may never be resolved."

"So if we are telling people that using condoms is what they need to do but we can't guarantee them that a condom will always be available, we may be setting them up for failure. "

Some other scientists who don't go that far - for example Professor Malcolm Potts of UC Berkeley - are also recommending more emphasis on behaviour change promotion to combat AIDS.

But all - including Hearst et al - told us they believe condoms are an essential component of an effective AIDS strategy and oppose the kind of general prohibition on condoms that Cardinal Trujillo advises.

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Promiscuity and risk-taking behaviour

This is a highly controversial area fraught with conflicting data and outright speculation.

Cardinal Trujillo claims condoms increase risk-taking behaviour.

"People think they're covered and they're not" as the Archbishop of Nairobi told Panorama in "Sex and the Holy City".

But as Professor Hearst says there is no conclusive evidence.

Some scientists have calculated that given a particular failure rate with condoms, certain levels of hypothetical increased sexual activity could lead to more AIDS cases.

But we could find no empirical data to prove this is actually happening.

Others have suggested that what's called "Risk Compensation Theory" could come into play. This is the idea that people are willing to take a level of risk for pleasure or reward, and if the risk is decreased - say by condoms - they will increase it back to the predetermined level they find comfortable, knowing they can now have more reward or pleasure in return.

If they're careful and well-informed the precautions they take will give them a similar level of risk but a greater reward - this is called "homeostatic" risk compensation.

But the suggestion is that people are ill-informed about the risk because they don't realize condoms may in practice not be 100% safe, and so unwittingly take on too much risk.

It would be rather like people thinking they're safe because of seat belts and then driving faster - leading to more fatal road accidents (it has been suggested that's happened in some countries, though that's very hotly disputed).

However, once again we could find no empirical data - or firm evidence from our own reporting on the ground - to support the speculation that this is happening in the AIDS pandemic.

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The conclusion

Condoms can significantly cut the risk of HIV infection, but are not perfect or foolproof.