The head of a Harvard-based AIDs prevention centre says the Pope is “correct” to claim that condom distribution risks aggravating the transmission of HIV.

Last week Benedict XVI incurred the wrath of AIDs campaigners and criticism from the Governments of France and Germany for saying, en route to Africa, that AIDS could not “be overcome by the distribution of condoms.” In comments condemned as "scary" and "alienating" by members of the International Planned Parenthood Federation, Benedict XVI lauded monogamy as a way to combat the spread of AIDs. He said that condom distribution risked exaggerating the spread of the virus.

Edward C. Green, director of the AIDS Prevention Center at the Harvard Center for Population and Development Studies said this week: “The best evidence we have supports the Pope’s comments."

In an interview with the National Review Online, Mr Green said: “We have found no consistent associations between condom use and lower HIV-infection rates, which, 25 years into the pandemic, we should be seeing if this intervention was working.”

He said condom distribution could lead to “risk compensation”, meaning that, once furnished with condoms, people were more likely to engage in riskier sexual behaviour.

Today, this claim was disputed as “ludicrous” by Michael Bartos, chief of the UN AIDs Aids Prevention Unit in Geneva

“It is like saying that sales of mosquito repellent are higher in places where people are more likely to get mosquito bites,” he said. "If people are using condoms more in areas where they are more likely to get HIV, that is positive."

He said there was no “empirical evidence” to show that greater availability of condoms led to an increase in risky sexual activity

Mr Green claimed that reducing "concurrency" or the custom of engaging in two, usually long-term sexual relationships at the same time was the key to successfully combating AIDS. He said: “The best and latest empirical evidence indeed shows that reduction in multiple and concurrent sexual partners is the most important single behavior change associated with reduction in HIV-infection rates (the other major factor is male circumcision).”

In an interview with The Times today, Mr Bartos said: “One thing that accounts for the very high AIDs transmission rate in South Africa is the low rate of male circumcision and the high rate of concurrent partnerships.”

He added: “Condom messaging needs to be more refined and needs to take into account the reality of people’s lives. However it is a false opposition to say [that it is a case of] either condoms or concurrent relationships or male circumcision." Condoms and programmes tackling concurrency and male circumcision, which can reduce the transmission of the HIV virus by up to 60 per cent, were both needed, Mr Bartos said. "Concurrency is a factor but not the master explanation for the spread of AIDs."

However, a leading author on the fight to combat AIDs today backed Mr Green’s theory. Dr Helen Epstein, author of The Invisible Cure, Why We Are Losing the Fight Against AIDS in Africa, said that concurrency can “give rise to a vast interlocking network of stable sexual relationships that serves as a virtual superhighway for HIV, placing at risk large numbers of people who may think they are safe because they are not typically “promiscuous”. For example, some men have two girlfriends or two wives, (or a wife and a girlfriend) with whom they sleep regularly. One or both of those women may have another regular partner – and those men may have other regular wives or girlfriends – and so on.”

A molecular biologist who has co-designed an AIDs prevention programme based on combating concurrency in partnership with the non-profit organisation Population Services International in Mozambique, Dr Epstein added: “In Africa most HIV transmission takes place in long term relationships. People use condoms in casual relationships, and with prostitutes, but that accounts for a relatively small part of the epidemic in the "AIDS epicentre" of East and southern Africa .”

She said the importance of reducing concurrency had been proved by Uganda's successful "Zero Grazing" AIDs prevention campaign, promoted in the late 1980s by its Government. "The tone was pragmatic, not moralistic, and this helped de-stigmatize the epidemic, and brought everyone into the campaign, including community and church groups, women’s groups, the media and ordinary people. As a result, sexual norms began to shift in favour of fewer sexual partnerships and more consistent condom use in casual sex.”

While she wished the Catholic Church would change its ban on condoms, Dr Epstein highlighted the role the Church could play in promoting collective change of sexual behaviour.

She said: "The [ Uganda ] program was based on a very African process of community mobilization, collective action, compassion and mutual aid. These are things the Church has always been good at. Indeed, the Church is often much better at promoting collective action than the public health community, which tends to take a more individualistic approach.”