The Need for New Vaccines

There is a constant demand for new and improved vaccines. Despite the success of current vaccines in controlling widespread epidemics, none of them demonstrates complete efficacy. In the case of cholera, the vaccine efficacy is around 50% and, as stated earlier, efficacy for BCG varies considerably. WHO figures for 2007 put the number of deaths from tuberculosis at 1.5 million. Although herd immunity may ultimately lead to eradication of some pathogens due to a reduced reservoir of infection, this is probably only attainable for pathogens where the only natural host is the human population. This was the case with smallpox and raises a similar prospect for polio and measles. Furthermore, there are no vaccines available for major diseases such as HIV/AIDS and malaria.
In 2007, there were 2.5 million new cases of HIV infection and 2.1 million deaths recorded. One child under 5 years of age dies every 30 s from malaria and there were 500 million cases of illnesses reported in 2007. The extent of these diseases inevitably results in co-infection.There were 200 000 deaths associated with HIV/tuberculosis in 2007, and the emergence of an extensively drug-resistant form of tuberculosis, XDR-TB, compounds the existing problem.