AIDS Vaccine       

The issue of HIV/AIDS has moved sharply up the international agenda in the last eighteen months. HIV is now regularly discussed at G8 summits. It is widely acknowledged that the HIV pandemic is setting back economic growth in the developing world, and threatens the social fabric of whole nations.

The supply of drugs is set to expand, hopefully rapidly, with the World Health Organisation having a target of 3 million people receiving treatment by 2005. But the drugs do not provide a cure. Also, however well we do in persuading more people to change their sexual behaviour and protect themselves against infection, HIV will not go away. The very nature of its transmission ensures that.

A vaccine which is safe and effective is essential if we are eventually to halt the global epidemic. Relatively little attention has been paid so far to vaccine development, with some people being sceptical that we can ever find one, although the general scientific consensus is that it can be done.

If we look at other diseases which used to be rampant, vaccines have been successful. Smallpox was eradicated over 20 years ago. Polio has disappeared in some parts of the world, and is on the way to being eliminated. Infections such as measles can be controlled.

Work on AIDS vaccines is going forward. Experimental vaccines have worked in non-human primates. We know also that a minority of people who are repeatedly exposed to possible HIV infection remain uninfected and produce HIV specific immune responses. If we could understand precisely why and how this occurs,  it would provide us with ideas on how a vaccine might work.

Development of a vaccine has not been a priority  for either private or publicly funded research. Pharmaceutical companies, including some with long experience in the filed of vaccines, have been slow to get involved. This is almost certainly related to the high costs of vaccine development, coupled with a relatively small market compared with that for drugs, as well as the countries with most need for a vaccine being poor. There are some signs of change, as two major companies, Merck Sharpe and Dohme and GlaxoSmithKline are now starting to invest in vaccine programs and to test potential products.

The UK Government was one of the first to fund the International AIDS Vaccine Initiative (IAVI).. IAVI was formed specifically to work to develop an effective vaccine. Through the work of an IAVI team in the UK and Kenya a candidate vaccine has now reached intermediate human trails, and may well move into phase 3 testing soon in east Africa. A small number of other candidate vaccines are reaching a similar stage. The first trials in South Africa could happen soon.

However the scale is still small. Only a few products are reaching serious trials. None of them is by any means guaranteed to succeed. In any case we urgently need to expand the number of potential vaccines. The fact that HIV exists in a number of strains means that a vaccine which succeeds in, say, the USA, might be ineffective against the common African strains. Yet the majority of candidate products so far tested, if only for safety, in humans have been related to North American and European strains of the virus.

We do not really know whether a vaccine would work for all the different strains and this must be part of the research. We cannot permit a situation to develop where we have a vaccine which works in rich countries but not in poor. That means work not just on different HIV strains, but on ensuring that any vaccine is stable and easy to deliver within a health care system which is limited.

Even a vaccine which was only partly effective could make a profound difference. A 50% rate of success in a country with high infection rates would stop large numbers of people becoming infected. A partially successful vaccine would also inevitably stimulate far more work to move on to better products.

Should we continue to look for a vaccine? The answer must be yes, simply because there is no other route to stopping HIV infections. We need more money into research, and a step change in the scale of the research work. It has increased in the last few years, but still represents less than 1% of spending on all health related research and development.

We must involve developing countries with high infection rates in the work, and help them to be central to the research and testing. It is unlikely that a solution is imminent, but some of those most closely involved believe we could have the first products on the market within a decade. That is a goal worth working towards.

June 2004

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