A Hopeful Beginning for Malaria Vaccines (New Eng Jour Med)

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A Hopeful Beginning for Malaria Vaccines
William E. Collins, Ph.D., and John W. Barnwell, M.P.H., Ph.D.

An effective human malaria vaccine has been sought for over 70 years, with little success.1

A successful malaria vaccine used in conjunction with other control interventions would help reduce and eventually eliminate the considerable global disease burden caused by malaria. Many different antigens have been identified as potential targets for malaria-vaccine development. One of these, the repetitive sequence of four amino acids in the circumsporozoite antigen on the surface of the sporozoite of Plasmodium falciparum, arguably the most important of the human malarias, is the basis for the RTS,S vaccine.2

This vaccine was subjected to extensive studies involving human volunteers, the results of which indicated a potential protective efficacy of about 40% when the vaccine was used in combination with an effective adjuvant therapy.3,4

Subsequently, a number of field studies have indicated that in endemic areas, this vaccine could have a rate of efficacy of about 30% against clinical disease and about 40% against new cases of infection.5,6 This is the first candidate malaria vaccine to show significant protection in laboratory- and field-based clinical studies.

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Although the results of Abdulla et al. and Bejon et al. are promising, the baseline incidence of malaria was low in each study area. Evaluations of vaccine-efficacy studies can be complicated by the introduction of insecticide-treated bed nets and artemisinin-based combination drug treatments through ongoing control programs across sub-Saharan Africa.10 Recent reports indicate that, in some areas in which malaria is endemic, such as in the Gambia in West Africa and Kenya and Tanzania in East Africa, there have been dramatic reductions in the malarial disease burden.11,12

However, as the RTS,S vaccine heads into phase 3 trials in 2009, large areas across Africa still have moderate-to-intense malaria transmission. Malaria transmission of yet higher intensity, with greater and more continuous assault by mosquito-injected sporozoites, could affect the efficacy of this vaccine.6 This is the first malaria vaccine to reach this stage of development, and it will be essential to learn how it performs in areas of more intense transmission. Only then will we have a clear idea of what effect it will have on the well-being of children in Africa and elsewhere and its role in malaria control. It is, indeed, a hopeful beginning.

Source Information

From the Malaria Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta. The opinions expressed in this article are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

The New England Journal of Medicine is owned, published, and copyrighted © 2008 Massachusetts Medical Society. All rights reserved.

http://content.nejm.org/cgi/content/full/NEJMe0808983?query=TOC

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1. Is 40% efficacy a good starting point?

My prediction: As global warming changes the workable environement for the Aedes aegypti mosquito to thrive and it creeps towards Europe a vaccine will successfully be developed to counter it:


Epidemiologists say that global warming is allowing the tiger mosquito, Aedes albopictus, a vector of both chikungunya and dengue fever, to survive in areas that were once too cold for it. This mosquito now thrives across southern Europe and even in France and Switzerland. All it takes is one infected traveler to bring the dengue virus home, where the bite of a resident tiger mosquito could transmit it to others.

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2. Yeah, 40% isn't a bad start. Especially when you translate that into lives saved.

Decreasing malaria and cholera (via available, clean drinking water) would save a lot of people, even in the face of inadequate nutrition or famine and HIV disease.