NEW DELHI: A malaria vaccine could be a reality by 2015. The most promising candidate now showing that it can protect children for 15 months.
The efficacy of the vaccine, whose phase-II trial results have just been published in the British medical journal " The Lancet", reduced from 53% for eight months (during the phase-I study in 2008) to 46% when it protected for 15 months.
Indian experts, however, claim that for a vaccine to be effective in the field, it has to give protection of over 75%. "At present, long-lasting insecticide treated bed nets give 60% protection, and it's per capital cost is very low. Hence, a vaccine has to be at least 75% effective," a vector borne disease control programme expert said.
The vaccine (RTS,S/AS01E) worked by attacking the malaria parasite in its early stages, when it first enters the bloodstream or liver cells, with the aim of completely preventing infection of red blood cells and the development of serious symptoms.
The latest study was established to assess the safety and efficacy of the vaccine against Plasmodium falciparum infection among healthy African children. Between March 2007 and October 2008, 894 children aged 5-17 months from Kenya and Tanzania were randomly assigned to three doses of either RTS,S/AS01E (447 children) or rabies vaccine (447). Blood samples were taken before vaccination, and at regular intervals.
During the phase-I study in 2008, initial results showed that the RTS,S/AS01E vaccine gave 53% protection against clinical malaria for at least eight months. In this study, the Kenya Medical Research Institute followed up the children for a further seven months
In the longer-term, the efficacy of the vaccine did not wane and protection against clinical malaria lasted for at least 15 months after vaccination.
Studies revealed children vaccinated with RTS,S/AS01E were 45.8% less likely to be infected with the P falciparum parasite. Frequent serious adverse events included pneumonia, febrile convulsion and gasteroenteritis.
However, fewer serious adverse events were reported in the RTS,S/AS01E group (11.4%) than in the rabies group (19.7%).
The authors maintain, "further studies are needed to establish vaccine efficacy in children with HIV infection or those who are malnourished. Furthermore, phase III studies should include study sites at different transmission intensities to confirm how generalisable our results are."
Late-stage trials of this vaccine among 16,000 children in seven countries across Africa are on, and immunisation is due to end in February. If data show the vaccine is effective, it could be licensed and rolled out in 2015.
Globally, around 300 million people become infected with malaria annually, and at least 2.5 million succumb to it -- primarily children in Africa and Asia. A child is killed by malaria every 30 seconds around the world. In India, on an average, five lakh people are affected and over 18,000 die of malaria. In some countries with a very heavy malaria burden, the disease accounts for as much as 40% of public health expenditure. Almost 60% of malaria cases occur among the poorest 20% of the world's population.
Malaria remains a major health problem in south-east Asia, and 83% of its population is at risk.
Read more: Malaria vaccine a reality by 2015? - The Times of India http://timesofindia.indiatimes.com/india/Malaria-vaccine-a-reality-by-2015/articleshow/7286785.cms#ixzz1B5N4Qr9T
The efficacy of the vaccine, whose phase-II trial results have just been published in the British medical journal " The Lancet", reduced from 53% for eight months (during the phase-I study in 2008) to 46% when it protected for 15 months.
Indian experts, however, claim that for a vaccine to be effective in the field, it has to give protection of over 75%. "At present, long-lasting insecticide treated bed nets give 60% protection, and it's per capital cost is very low. Hence, a vaccine has to be at least 75% effective," a vector borne disease control programme expert said.
The vaccine (RTS,S/AS01E) worked by attacking the malaria parasite in its early stages, when it first enters the bloodstream or liver cells, with the aim of completely preventing infection of red blood cells and the development of serious symptoms.
The latest study was established to assess the safety and efficacy of the vaccine against Plasmodium falciparum infection among healthy African children. Between March 2007 and October 2008, 894 children aged 5-17 months from Kenya and Tanzania were randomly assigned to three doses of either RTS,S/AS01E (447 children) or rabies vaccine (447). Blood samples were taken before vaccination, and at regular intervals.
During the phase-I study in 2008, initial results showed that the RTS,S/AS01E vaccine gave 53% protection against clinical malaria for at least eight months. In this study, the Kenya Medical Research Institute followed up the children for a further seven months
In the longer-term, the efficacy of the vaccine did not wane and protection against clinical malaria lasted for at least 15 months after vaccination.
Studies revealed children vaccinated with RTS,S/AS01E were 45.8% less likely to be infected with the P falciparum parasite. Frequent serious adverse events included pneumonia, febrile convulsion and gasteroenteritis.
However, fewer serious adverse events were reported in the RTS,S/AS01E group (11.4%) than in the rabies group (19.7%).
The authors maintain, "further studies are needed to establish vaccine efficacy in children with HIV infection or those who are malnourished. Furthermore, phase III studies should include study sites at different transmission intensities to confirm how generalisable our results are."
Late-stage trials of this vaccine among 16,000 children in seven countries across Africa are on, and immunisation is due to end in February. If data show the vaccine is effective, it could be licensed and rolled out in 2015.
Globally, around 300 million people become infected with malaria annually, and at least 2.5 million succumb to it -- primarily children in Africa and Asia. A child is killed by malaria every 30 seconds around the world. In India, on an average, five lakh people are affected and over 18,000 die of malaria. In some countries with a very heavy malaria burden, the disease accounts for as much as 40% of public health expenditure. Almost 60% of malaria cases occur among the poorest 20% of the world's population.
Malaria remains a major health problem in south-east Asia, and 83% of its population is at risk.
Read more: Malaria vaccine a reality by 2015? - The Times of India http://timesofindia.indiatimes.com/india/Malaria-vaccine-a-reality-by-2015/articleshow/7286785.cms#ixzz1B5N4Qr9T
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