Stored blood samples show that subtype E was already identified at the beginning of the epidemic in Central Africa and as early as 1989 in Thailand. It is almost certain that new HIV genetic subtypes will be discovered in the future, and indeed that new subtypes will develop as virus mutation continues to occur. The current subtypes will also continue to spread to new areas as the global epidemic continues. However, in some countries there is very little monitoring undertaken to detect new sub-types. For example, in Britain, the government's Public Health Laboratory Service which is responsible for monitoring the spread of HIV in Britain, only analyses 2 new infections a month for sub-type information.
More research needs to be undertaken.
It is not known whether the genetic variations in subtype E or other subtypes actually make a difference in terms of the risk of transmission or the response to antiviral therapy. Inevitably, different types of candidate vaccines will have to be tested against various viral subtypes in multiple vaccine trials, conducted in both high-income and developing countries. In the long term, a safe, effective and affordable preventive vaccine against HIV is the best hope of bringing the global epidemic under control. However, it would be a mistake to think that the development of such a vaccine will be quick or easy or to expect that once a vaccine is available it will replace other preventive measures. Scientists are working to understand the kind of immunity a vaccine would have to induce in order to protect someone against HIV infection.