JOHN is HIV-positive and in a relationship with someone who is not. Two years ago, they stopped using condoms. They had become aware of a groundswell of evidence that people like John, who take their HIV medicines every day, have a negligible risk of passing on the virus.
“I used to struggle with this feeling that even the blood running in my veins was toxic,” says John. “Having this intimacy with my partner is such a big relief.”
The message that people taking their meds are effectively uninfectious is now being promoted by activists, campaigners and researchers at the highest level. “Once you begin therapy and you stay on therapy, you are not capable of transmitting HIV to a sexual partner,” said , who heads the Division of AIDS at the US National Institutes of Health at a .
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Although some researchers remain sceptical, in the UK, the message is being translated into official guidance for doctors that is .
For the average person, this new reality might come as a bit of a shock: has HIV really become an disease you can’t pass on?
It’s a dramatic turnaround. In the 1980s, an HIV diagnosis was tantamount to a death sentence. Many countries launched stark advertising campaigns warning people that they risked their lives having sex without condoms.
Then came the development of antiviral drugs that stop HIV from reproducing – arguably one of the greatest medical success stories of the 20th century (see diagram). The treatment cannot eliminate HIV from the body – the virus lurks inside dormant immune cells in lymph nodes and other tissues – but the life expectancy of people on therapy is near normal.
These medicines have another, more surprising effect: they reduce an infected person’s risk of passing on the virus to sexual partners (see “HIV in retreat“).
Just how much the risk falls has only recently become clear, after several studies of couples in monogamous relationships, in which one partner is HIV-negative and the other positive and on treatment.
“After 58,000 acts of sex without condoms, there were zero cases of HIV transmission”
Doctors check that the drugs are working by measuring the amount of virus in the positive partner’s blood. In those who are on treatment, levels are typically less than 50 per millilitre, the limit of detection for one of the main tests used – so the virus is said to be undetectable in the blood. In time it’s also undetectable in semen and genital fluids.
Does this keep the negative partner safe? Last year, results from the were unambiguous. It tracked nearly 900 gay and straight couples, where one partner was positive, through 58,000 acts of sex without condoms. As long as the person stayed on their meds for six months, and the virus was undetectable, there were no cases of HIV transmission.
These findings were supported by another . As well as the new UK guidelines for doctors, the trial results have triggered grass-roots campaigns to spread the word about “treatment as prevention”, including a US campaign called . Similar advice went up last month on a UK website about HIV prevention called .
But there are concerns. For one thing, not everyone who has HIV is on medication or has undetectable virus, a detail that could get lost in the enthusiasm. “A lot of people feel that this is a licence not to use condoms,” says of Johns Hopkins School of Medicine in Baltimore, “and that puts individuals at risk of [other] sexually transmitted diseases.”
Although these are generally less serious than HIV, Quinn points out that gay men are at higher risk of hepatitis B, which can require lifelong treatment, and hepatitis C, which can be cured but the medicines can have side effects. There’s also no cure for genital herpes.
Monogamy focus
For these reasons, relying on treatment as prevention is usually considered a good option only in monogamous relationships, where the HIV-positive partner may have extra motivation to take their pills every day. John, for instance, takes his three tablets at 9 am every day, and his partner usually sees him do it, or hears his reminder alarm. If he were to start missing doses, John’s viral load would rise, making him infectious again.
Even for people who are rigorous about taking their medication, however, there is another source of uncertainty: the possibility of a small and transient increase in their viral loads, typically going up to 200 per millilitre, sometimes up to 1000. We don’t know what causes them. One theory is such “blips” are just random fluctuations in a person’s virus levels, so sometimes it’s lower and sometimes . Others think they are due to some infection such as flu, or a sexually transmitted infection, . This might awaken dormant immune cells and prompt virus levels to increase.
Does a blip raise the risk of infection? “The risk is extremely low,” says Anthony Fauci, who heads the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland. However, he says, “It’s very difficult to say zero.”
But others say the risk is so low it can be effectively ignored. A viral load of 1000 sounds a lot compared with under 50, but it’s much less than in people who are undiagnosed and not on treatment, typically around 35,000. In fact, it’s thought that most HIV is passed on by people in the first few months after they are infected – before they know – and when their viral load is higher still, often several million. According to some models, it’s not even possible to pass on HIV with a viral load of under 400, while other studies place the cut-off higher still, at 1500.
While some blips nudge above these thresholds, the risk from such low levels is less than using condoms with someone who is not being treated for their HIV – because condoms can break or slip off, or not be used properly, says Dieffenbach. Yet the message that condoms are an effective defence against HIV is shouted from the rooftops, unlike the hesitation over treatment as prevention.
“The new reality will have implications for adoption and for conceiving children”
“That’s a contradiction, says of the London School of Hygiene and Tropical Medicine, who runs the Prepster website. “People are being cautious but we should apply that caution equally across all forms of prevention – instead of seeing condoms as the holy grail.”
The bottom line should be the data, says Dieffenbach. People in the Partner study and HPTN052 must have had blips between blood tests – and yet still there was no transmission between couples.
While some researchers continue to debate the data, forthcoming guidelines drawn up by three sexual health organisations say that for straight people in monogamous relationships whose HIV is undetectable, there is no risk in not using condoms, and that for gay people in the same circumstance the risk is “incredibly low”. The message could not be more welcome for HIV activists. And it’s not just about their sex lives.
“This has the potential to transform the way we think about HIV,” says Matthew Hodson of UK charity NAM. HIV remains one of the most stigmatised of all viral infections, a hangover from the days before effective treatment, when the disease was defined by doom-laden advertising full of tombstones, says Hodson. As a result, he says, “many who live with the virus face not just sexual but also social rejection”.
The new thinking, they hope, will reduce fear and stigma. If a person’s virus levels are undetectable, it means they will not be able to pass it to healthcare professionals or anyone else.
This could affect the decisions of social workers who may have previously been reluctant to grant approval to HIV-positive adoptive parents. It also means that people trying to conceive their own children no longer need to take special precautions, such as the uninfected partner taking HIV blockers.
“When we are undetectable we are uninfectious,” says Hodson. “This means that pretty much all the fear that HIV-negative people have of those of us living with HIV is just wasted energy.”
HIV in retreat
WE STILL have no cure and no vaccine, but HIV’s days as a public health problem could be drawing to a close in some Western countries. For the World Health Organization that would mean the rate of new infections has dropped to less than one per thousand people a year.
How will this be achieved? Simply by upping the number of HIV-positive people who are diagnosed and taking their medicines. This slashes levels of the virus in their blood, and so they are unlikely to pass the infection on to others (see main story).
If that sounds unrealistic. Denmark is nearly there already. Annual rates of new infections in gay men – the group at highest risk in this country – have fallen to 1.4 per thousand.
Replicating Denmark’s vigilance elsewhere could be a lot harder, though, and not just in poorer countries.
Denmark’s achievement stems from its universal healthcare system, which offers free treatment and easy access to testing.
The conscientious Danes are also very good at taking their HIV drugs every day – 98 per cent of those diagnosed report steadfast adherence to their daily regime. Statistical models suggest there are now only 617 undiagnosed HIV-positive gay men in the country.
This article appeared in print under the headline “A farewell to condoms”
Article amended on 9 February 2017
We have corrected a quote from Matthew Hodson
