Immunization, Vaccines and Biologicals

Malaria

Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected mosquitoes. According to the latest estimates, there were about 219 million cases of malaria in 2010 (with an uncertainty range of 154 million to 289 million) and an estimated 660 000 deaths (with an uncertainty range of 490 000 to 836 000). Indeed, the disease accounts for 20% of all childhood deaths in sub-Saharan Africa. While most malaria cases and deaths occur in sub-Saharan Africa, Asia, Latin America and, to a lesser extent, Europe and the Middle East are also affected.

Symptoms of malaria appear seven days or more (usually 10-15 days) after the infective mosquito bite. The first symptoms — fever, headache, chills and vomiting — may be mild and difficult to recognize as malaria. If not treated within 24 hours, Plasmodium falciparum (the most deadly form of human malaria) can progress to severe illness, often leading to death.

The complexity of the malaria parasite makes development of a malaria vaccine a very difficult task. Given this, there is currently no commercially available malaria vaccine, despite many decades of intense research and development effort. The most advanced vaccine candidate against Plasmodium falciparum is RTS,S/AS01. A phase 3 trial began in May 2009 and has completed enrollment with 15 460 children in the following seven countries in sub-Saharan Africa: Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique, and the United Republic of Tanzania. There are two groups in the trial: 1) children aged 5-17 months at first dose receiving only the RTS,S/AS01 vaccine; and 2) children aged six - twelve weeks at first dose who receive the same malaria vaccine doses in co-administration with pentavalent vaccines in the routine immunization schedule. Both groups receive 3 doses of RTS,S/AS01 vaccine at 1 month intervals.

Based on the current trial schedule, the phase 3 trial data required in order for WHO to consider making a policy recommendation is expected to be made available to WHO in late 2014. Depending on these full phase 3 results, the first WHO policy recommendations on use may occur in 2015.

The Malaria Vaccine Technology Roadmap set the goal for a "second generation" malaria vaccine with 80% efficacy to be developed and available by 2025. This is feasible if WHO member states and donor agencies invest in malaria vaccine research & development, and work to share information through a collaborative framework. The 2025 vaccine will need to have a substantial impact on transmission if it is to contribute to malaria elimination and the long-term aim of global malaria eradication.

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Last updated: 21 March 2013

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