On Sunday 5 June it will be 30 years exactly since the first scientific report of a mysterious outbreak of pneumonia among a group of five gay men at three different hospitals in Los Angeles. The study, published in the Morbidity and Mortality Weekly Report of the US Center for Disease Control, marked the start of what later became known as the Aids epidemic, which has since consumed millions of lives around the world.
In many ways, the past 30 years of Aids research has been a triumph of science. Soon after that initial report, epidemiologists were able to point to an infectious agent as the cause of the immune failure leading to the range of opportunistic infections known as Aids. Within three years, virologists had pinned the blame for the infection on a new human retrovirus, later named formally by an international committee of virologists as the human immunodeficiency virus (HIV).
Just a decade later, with all the power of modern molecular biology brought to bear on the problem, we learnt about HIV's highly variable genetic structure and how the virus was able to trick its way out of counter-attacks launched by the human immune system. But science developed anti-retroviral drugs to block its replication, and doctors devised a treatment regime, known as ART, that over the past decade has transformed the lives of people infected with the virus.
People with HIV are no longer considered to be "dying of Aids", but "living with HIV". Indeed, so successful are the anti-retroviral drugs that scientists are now looking at them not just as a palliative treatment for the individual, but as a way of controlling viral transmission within society.
The latest study, published earlier this month, shows that if you give anti-retrovirals early enough to infected people, there is a stunning 96 per cent reduction in HIV transmission to uninfected partners. The trial, involving nearly 2,000 couples, was stopped early because the results were so promising. Indeed, the study was called a "game-changer" in terms of controlling the epidemic.
This all stands in sad contrast to the dismal efforts at producing an Aids vaccine. Despite the fact that hundreds of millions of pounds have been spent on trying to develop a vaccine over the past three decades, there has been nothing like the scientific success seen in other areas of HIV research.
The story of the search for an Aids vaccine demonstrates that science cannot always come up with all the answers. Sure enough, science can tell us why it is particularly difficult to make an HIV vaccine – down to the virus's inherent variability and the fact that it attacks the body's immune cells themselves – but it hasn't been able to offer a viable solution.
Never giving up on trying to develop an Aids vaccine is laudable. But I can't help but think that the costs of continuing the effort may just outweigh the benefits, both in terms of the money that could be spent on better ways of curbing the epidemic and in terms of the huge number of laboratory animals, especially primates, that are "sacrificed" to the cause.
I know this idea is highly unwelcome to many people, but would it be right to spend hundreds of millions more on trying to make an Aids vaccine over the next 30 years when anti-retrovirals may hold the key to eliminating the epidemic once and for all? It is a question that we should at least consider.
The magic of Darwin's letters
One of my most treasured possessions is two volumes of letters written by Charles Darwin, and beautifully published by Cambridge University Press. You can dip into them at random and pick up the thread of many an interesting narrative. It is sometimes difficult to comprehend in this age of emails and Twitter just how important letter writing was to 19thcentury intellectuals. Darwin wrote and received something like 15,000 letters, and these are only the ones we know about. Many others may have been lost to history.
My two volumes are part of an 18-volume set comprising The Correspondence of Charles Darwin, which is in the process of being made available online in a project that is due to be completed in 2022.
I'm sure that accessing the entire canon of online correspondence will prove to be invaluable for anyone interested in following Darwin's train of thought as he discussed his ideas with his contemporaries. But there is nothing quite like the sheer luxury of sitting down with the printed version of the words, which were, after all, written by hand and designed for someone's personal perusal.
What else doesn't Hawking believe in?
News that Stephen Hawking does not believe in Heaven, published with much excitement in another newspaper this week, comes hot on the heels of his early pronouncement, in a different newspaper, that he does not believe in God.
Now I would have thought that it would be taken as given that someone who does not believe in God would also find it difficult to believe in Heaven. To have a Heaven without a God seems odd to me, but there again, like Stephen Hawking, I'm no theologian.
Look out for the next instalment of the list of things that Stephen Hawking does not believe in.
Fairies at the bottom of the garden perhaps?