It's National HIV Testing Week again. But this year it seems strangely different, a real mix of ups and downs. The week in which Charlie Sheen was first hounded by the tabloid press and then disclosed his HIV status demonstrated how ruthless society can be - and the stigma that people with HIV still have to endure.
At the same time, there is a sense of optimism that I haven't felt for a long time. More positive people than ever are standing up and saying, "I'm HIV positive, and I'm OK." I'm proud to say that at the forefront of this effort are positive ambassadors associated with Saving Lives, the charity of which I am medical director: from Angelina in Marie Clare to Tom on Newsnight and Beck in The Sun. These individuals have stood up in the national press and really talked about not being ashamed of being HIV positive.
But believe me, this remains extremely difficult to do. For the patients I see, stigma continues to be the number one issue that deters them from disclosure.
But there's another thing - and I think a gamechanger. That is the publication this year of several studies which have clearly shown that antiretroviral therapy profoundly reduces the risk of transmitting HIV to another person whilst you are on treatment. The chance is virtually zero.
This has been hugely empowering to people living with HIV. Not only that, but for the first time I've seen data this week that people on successful treatment have a life expectancy the same as the general population.
Unfortunately, this is not true for too many people - for people living in countries in which poor infrastructure does not allow them to gain access to effective therapies, and for the undiagnosed everywhere. Without a doubt, undiagnosed and untreated HIV remains a life-threatening condition.
In this context, what has the Charlie Sheen incident taught us? It's clear from the vitriol in the press and even from certain factions of the public that HIV is still seen in some quarters as a punishment from God or fate, afflicted on those who are deserving of it.
There is so much misinformation about the condition. And this year, there seem to me three key messages which we can use to dispel a whole conglomeration of damaging myths.
1. HIV is not the same as AIDS.
This is a simple but important distinction. HIV is a virus - the human immunodeficiency virus. AIDS, on the other hand, stands for Acquired Immune Deficiency Syndrome. The HIV virus attacks and damages the bodies immune cells, leading the immune system to become progressively weaker. At a certain point, the immune system becomes unable to fight off what we call opportunistic infections - infections which healthy people would be able to deal with. When a person has developed enough of these opportunistic infections, they are said to have developed AIDS.
This may have been relevant in the 1980s, when a diagnosis of HIV meant one thing - that you were going to die, probably with six months to a year of diagnosis. Today, somebody can develop one of those opportunistic infections - and be successfully treated. Today's treatment can rebuild immune systems. In this context, late diagnosis, which has ten times the mortality rate of early diagnosis, is our main enemy (in the UK, 50% of heterosexuals are currently diagnosed late). Today, we should properly refer to 'people living with HIV' or 'people diagnosed with advanced HIV'. And yet the word 'AIDS' seems still to carry this stigma.
2. Having sex with someone who has HIV may not mean you will contract HIV.
This is a tricky one. The sexual transmission of HIV is an extremely complicated subject and depends upon a very wide range of factors. Without a doubt the most important of these are the use of condoms and the amount of virus in a person's body.
We know that condoms are extremely effective in preventing the spread of HIV, and we should continue to encourage their use. On a scientific level, however, what are the risks of transmitting HIV?
The big game-changer came from the interim results of the PARTNER study, a study which took almost 900 couples, both men who have sex with men and heterosexuals, one of whom was positive and the other negative. The positive partner was fully suppressed on treatment, and the couples were having unprotected sexual intercourse.
The startling results in the interim data? After 23,000 episodes of unprotected sex, there have so far been no sexual transmissions at all. This does not mean it can't happen, and the longer the study continues the greater will be our confidence in these results; however, this headline figure gives you an idea of the magnitude of the effect of antiretroviral therapy.
We can contrast this with having sex with someone who has HIV and does not know and is therefore not on treatment; they might also have another sexually transmitted infection they are unaware of. One of the earliest studies suggested a huge range of risk, from up to 50% with casual partners down to less than three in a thousand.
Why such a huge range? Again, it depends on the person: have they just been infected themselves? Do they have high levels of virus in their system? Do they have other STIs which facilitate the transmission of HIV? And what type of sex do the couple engage in? (Receptive anal sex still gives the highest risk of transmission.)
Who are you more likely to catch HIV from, then? A person who is diagnosed, on treatment, and open about their status - or a person who does not wish to know their status, is not on treatment, may have other STIs, and have huge amounts of virus in their body? We know that the vast majority of new infections of HIV in the UK come from those individuals who are undiagnosed themselves.
3. There's never been a better reason for people to get tested.
By taking a test, an individual looks after their own health, stops themselves from becoming sick and possible dying; but also has a huge impact on the spread of HIV within the community.
Not having an HIV test puts your life at risk, and those of others. So the message of this NHTW is very clear: we must reduce the stigma around HIV. Healthy people with HIV must talk about it; the general public must become educated about HIV; and we need to test as many people as possible.
The ambitious aims of the 90/90/90 programme (90% of people tested, 90% on treatment, 90% undetectable by 2020) poses a challenge to us all: but everyone can do their bit this National HIV Testing Week to make the goal possible.
The charity I work with, Saving Lives, is contributing to this effort by creating a confidential, reliable postal HIV testing service. It is being made free for the first thousand people to request a kit during National HIV Testing Week.
It is within our grasp to control HIV, defeat the stigma that still surrounds it, and make individuals and the community alike healthier. National HIV Testing Week is a great opportunity to demonstrate how.