As an international conference of HIV and Aids experts comes to a close in Mexico City, Genevieve Edwards of the Terrence Higgins Trust reports on what has been learnt about the latest challenges in the fight against the disease.
The criminalisation of HIV must end.
That was the closing call from the conference of experts and campaigners meeting in Mexico City.
The man who made the demand was Justice Edwin Cameron, a High Court judge from South Africa.
He is a well-known and greatly respected figure and, remarkably, the only high-ranking government official in the whole of Africa to be openly HIV positive.
Delegates from all over the world with differing laws, variously applied, have warned that punitive laws are on a collision course with public health.
Far from helping reduce transmission, there is mounting evidence that they harm testing and prevention initiatives and increase stigma for people living with HIV.
'Drugs for all'
Justice Cameron's global campaign is likely to gather significant momentum.
Eight years ago, he used the same conference stage to call for universal access to HIV treatment for everyone who needs it.
Today, three million people in developing countries have access to HIV drugs, and the target is for universal access by 2010.
The drugs themselves have improved immeasurably since they were first introduced in 1997.
Instead of the 30 or so pills a day people took in the past, they'll probably now take just one.
We also heard at the conference of the benefits of combining prevention methods.
Promoting condom use, male circumcision, access to HIV testing, reducing numbers of new partners, and providing clean needles for injecting drug users all help reduce new HIV infections.
And what has been incredibly exciting is the role that HIV treatments can have in preventing new transmissions.
We know that giving pregnant women HIV drugs can reduce the chances of her baby being born with HIV to just 2% worldwide.
The challenge now is to make sure they are available to all women who need them. Currently just 30% do.
The possibility that successful HIV treatment can make it unlikely that someone can pass the virus to others has been hotly debated.
Some experts say yes, if you are adhering to a successful treatment regime which has suppressed the virus to an undetectable level and have no other sexually transmitted infections.
Kevin De Cock, from the World Health Organisation, talked about the strong and indivisible coalition between treatment and prevention.
Others point out the unpredictability of "viral blips", particularly caused by other infections, or failure to adhere perfectly to treatment regimes.
So far, research has only concentrated on a small number of heterosexual couples. We don't yet know how it might work for men who have sex with men.
But with the great majority of people with HIV globally either untested, or unable to access HIV drugs, treatment as prevention remains a pipe dream for all but a very few.
Five to two
Jaime Sepulveda from the Bill and Melinda Gates Foundation said that the turning point in the HIV epidemic will be when more people are starting on treatment in a year than are newly infected.
At present, infections outpace those newly on treatment by five to two.
In the UK however, where treatment is available to most, this has real implications for our HIV prevention programmes. We are all keen to get home and start work.
The search for a vaccine for HIV was recently derailed with the failure of a trial being run by Merck.
Early over-optimism has led to scepticism among many here about the likely success of vaccine initiatives.
Yet a lack of confidence in vaccine development may harm funding and talent going into the field - which experts at the conference admitted are vital.
What's not in doubt is their certainty that they will succeed.
As Seth Berkley from the International AIDS Vaccine Initiative said: "What keeps me going is knowing it is important and right and science will prevail".
There has been much to learn here in Mexico City. But perhaps the greatest lesson is that we will succeed only with the involvement, at every level, of people living with HIV.
Activists have always played a vital part in the HIV epidemic.
They have fought for treatment, for the protection of rights, for access to healthcare and much, much more.
As we prepare to leave Mexico City, it is the alliance of activists, scientists, policy makers and funders that will make the difference between what we are doing, and what we are capable of.