In the mid-1990s, the development of anti-retroviral drugs was hailed as the answer to a modern plague. By converting a lethal infection into a chronic disease, which sufferers could live with rather than die from, they transformed the outlook for millions.

What was not realised then, and is only now becoming clear, is that the drugs which spared sufferers a death sentence also helped reduce, and virtually eliminate, transmission of the virus. One early anxiety among researchers was that while extending the lives of those infected with HIV was clearly a triumph, it risked worsening the pandemic because the longer infected individuals lived the more time they had to pass the virus on.

That has turned out, thankfully, not to be true. Instead, antiretroviral drugs extend life by delaying the progression from HIV to Aids while at the same time curbing the spread of the infection by reducing the viral load. It is treatment and prevention in one.

After decades of searching for a magic bullet to end the global pandemic, it may be that our best weapon was lying in front of our noses all the time. If treatment with antiretrovirals can be extended beyond the four million sickest individuals who currently receive it, we could substantially slow the spread of the virus – and perhaps even ultimately eliminate it.

The limiting factor is cost. The expense of keeping the 33 million people infected globally with HIV on drugs for life would be enormous. But so will be the cost of not doing so – when measured in terms of the treatment and care they will require in the future.

If universal treatment is beyond our grasp, there is still more that we can do. These are safe drugs, with few side effects which require little monitoring. A study published in The Lancet six months ago concluded that routine laboratory testing for signs of side effects – long regarded as essential for HIV treatment – was unnecessary and a waste of time and money.

By abandoning routine testing, which is costly and requires sophisticated equipment only available in hospitals, the money saved could be used to buy and distribute drugs to an extra one million people. That would not close the gap between what is currently being done and what should be done – but it would narrow it.

Further investment of effort and resources will still be needed. But at least we know the end we are aiming at. The task we are left with is to will the means.