Development of new drugs and vaccines
Chart: In the pipeline
Intervention: Providing finance for malarial drugs
|Over the past few decades we have learnt to our cost that diseases are an ever-moving target. Dangerous microbes adapt to survive. And we must always be one step ahead if we too are to survive. The race is on to find new low-cost tools which can be used not only to step up the prevention of diseases, but to improve and accelerate their diagnosis and treatment as well.
In drug development, urgent efforts are under way to develop new drugs to treat diseases like malaria, tuberculosis and pneumonia which are rapidly becoming resistant to first-line drugs. Without a new generation of low-cost drugs, some diseases could become untreatable in countries which cannot afford to buy more expensive second-line drugs. Also being tested are new combination therapies to treat diseases such as lymphatic filariasis, river blindness and malaria - using more than one drug to increase effectiveness and lower the risk of developing drug-resistance. Other priority drugs include a new oral drug which could help reduce deaths from visceral leishmaniasis and a new, non-injectable, quick-acting drug to treat severe cases of malaria.
Top of the global priority wish-list in vaccine development today are vaccines against acute respiratory infections, diarrhoeal diseases, HIV/AIDS, malaria, tuberculosis and dengue.
Of these, a vaccine against HIV/AIDS is arguably the most important since no cure exists and mortality is high. For people living with HIV/AIDS today the disease is still fatal, although some have access to life-prolonging drugs.
Efforts are also under way to reach the one in five children who are still not immunized each year through national immunization programmes. This includes efforts to lower vaccine delivery costs, simplify the administration of vaccines, and reduce the number of immunization contacts needed.
Until recently, research has been hampered by the lack of animal models to test vaccines and by the ability of the virus to mutate with every new infection. As most initial vaccine research focused on the type of virus most common in North America and Europe, research must now be intensified on virus types from developing countries, where over 90% of infections occur.
A new, improved vaccine would be a major breakthrough in preventing pneumococcal pneumonia - the biggest childhood killer.
Four manufacturers are now carrying out clinical trials on new pneumococcal vaccines. The most promising are modelled after the Hib conjugate vaccine which has been highly successful in reducing bacterial meningitis and pneumonia in the industrialized countries.
A large number of malaria vaccines are under development. Several of the more advanced are now being tested in Asia, Africa and the United States. The most extensively studied is a vaccine developed in Colombia (SPf66). Although initial promising results have so far not been replicated in other studies, this vaccine has now been modified to increase its potency. And there are hopes that this second-generation vaccine could provide the much-needed breakthrough in malaria prevention. Another advanced-stage vaccine, which might be able to prevent the onset of disease in someone already infected, is now being tested in the Gambia and Kenya. The cost of developing a malaria vaccine has been estimated at $50 million over the next 10 years.
New antimalarial drugs
Another promising new product is a suppository (artesunate) for malaria sufferers who are too sick to take oral medication. It is quick-acting, easy to administer and can "buy time" for people with severe malaria living in remote areas who might not survive the journey to hospital.
Diagnostic tests for sexually transmitted infections (STIs)
Women are biologically more vulnerable than men to sexual transmission of HIV and account for 75% of all new infections today. Unlike the female condom, which is visible, vaginal microbicides could be used without a male partner's consent.
|© World Health Organization 1999
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