Malaria vaccine shows encouraging results in children
http://www.100md.com
《英国医生杂志》
A malaria vaccine has shown encouraging results in children, according to a phase II study published last week (Lancet 2004;364:1411-20).
The study investigated the efficacy of a malaria vaccine, RTS,S/AS02A, directed against the Plasmodium falciparum sporozoite, the form of the malaria parasite that is injected into the human bloodstream by mosquitoes. The study was conducted on two cohorts of children aged 1-4 years living in Mozambique. Each cohort was divided into two groups, and the members of each group were randomly allocated to three doses of the malaria vaccine given intramuscularly or to control vaccines, including pneumococcal and hepatitis B vaccines.
The first cohort (1605 children) was followed up for six months to assess the efficacy of the vaccine in preventing clinical episodes of malaria. The second cohort (417 children) was followed up for longer to test the effect on preventing subsequent new infections.
The risk of developing at least one episode of clinical malaria was reduced by 29.9% (95% confidence interval 11.0% to 44.8%) during the six months of follow up among children given the malaria vaccine compared with children given control vaccines; 57.7% fewer children developed severe malaria (16.2% to 80.6%). In the second cohort, the malaria vaccine extended the time to first infection by 45.0% (31.4% to 55.9%).
One of the research group, Pedro Alonso, head of the epidemiology research unit, Centre de Salut Internacional, University of Barcelona, Spain, and Manhi鏰 Health Research Center, Mozambique, said, "These are clearly the best results we have ever seen with a candidate malaria vaccine. They indicate the feasibility of development of an effective vaccine against malaria."
He said it would have been unrealistic to expect the vaccine to prevent 100% of infections. "Just like any other malaria control tool that we have, like insecticide treated nets. . . none of them is 100% effective. Control will rely on using a combination of malaria control tools together. We believe a malaria vaccine, even of moderate efficacy, could make a huge impact."
The vaccine was well tolerated. Local and general symptoms, including injection site reactions and fever, were more common than with control vaccines, but did not result in withdrawals from the study. More than 92% of children received all three doses. The vaccine was also considered safe, with vaccinated children having fewer serious adverse events, hospital admissions, and severe complications from malaria than the control group. It proved to be highly immunogenic, especially in children younger than two years.
The research was funded by GlaxoSmithKlineBio and a global project, created through a grant from the Bill and Melinda Gates Foundation, to overcome barriers to malaria vaccine development—the PATH Malaria Vaccine Initiative.
In the same issue of the Lancet, in a commentary (p 1380-2), Philippe van de Perre and Jean-Pierre Dedet of the University of Montpellier, France, said, "The recent history of vaccinology tells us that vaccine development is a desperately long process. Decades are often needed from the preclinical testing of candidate vaccines to licensing and public availability.
"The current unprecedented public-private partnership for the development of malaria vaccines, with national and international agencies sharing the goals, should speed this process as much as possible and boost innovations." They predicted that the RTS,S/AS02A vaccine might be licensed by 2010 if further trials continued to show good results.(London Susan Mayor)
The study investigated the efficacy of a malaria vaccine, RTS,S/AS02A, directed against the Plasmodium falciparum sporozoite, the form of the malaria parasite that is injected into the human bloodstream by mosquitoes. The study was conducted on two cohorts of children aged 1-4 years living in Mozambique. Each cohort was divided into two groups, and the members of each group were randomly allocated to three doses of the malaria vaccine given intramuscularly or to control vaccines, including pneumococcal and hepatitis B vaccines.
The first cohort (1605 children) was followed up for six months to assess the efficacy of the vaccine in preventing clinical episodes of malaria. The second cohort (417 children) was followed up for longer to test the effect on preventing subsequent new infections.
The risk of developing at least one episode of clinical malaria was reduced by 29.9% (95% confidence interval 11.0% to 44.8%) during the six months of follow up among children given the malaria vaccine compared with children given control vaccines; 57.7% fewer children developed severe malaria (16.2% to 80.6%). In the second cohort, the malaria vaccine extended the time to first infection by 45.0% (31.4% to 55.9%).
One of the research group, Pedro Alonso, head of the epidemiology research unit, Centre de Salut Internacional, University of Barcelona, Spain, and Manhi鏰 Health Research Center, Mozambique, said, "These are clearly the best results we have ever seen with a candidate malaria vaccine. They indicate the feasibility of development of an effective vaccine against malaria."
He said it would have been unrealistic to expect the vaccine to prevent 100% of infections. "Just like any other malaria control tool that we have, like insecticide treated nets. . . none of them is 100% effective. Control will rely on using a combination of malaria control tools together. We believe a malaria vaccine, even of moderate efficacy, could make a huge impact."
The vaccine was well tolerated. Local and general symptoms, including injection site reactions and fever, were more common than with control vaccines, but did not result in withdrawals from the study. More than 92% of children received all three doses. The vaccine was also considered safe, with vaccinated children having fewer serious adverse events, hospital admissions, and severe complications from malaria than the control group. It proved to be highly immunogenic, especially in children younger than two years.
The research was funded by GlaxoSmithKlineBio and a global project, created through a grant from the Bill and Melinda Gates Foundation, to overcome barriers to malaria vaccine development—the PATH Malaria Vaccine Initiative.
In the same issue of the Lancet, in a commentary (p 1380-2), Philippe van de Perre and Jean-Pierre Dedet of the University of Montpellier, France, said, "The recent history of vaccinology tells us that vaccine development is a desperately long process. Decades are often needed from the preclinical testing of candidate vaccines to licensing and public availability.
"The current unprecedented public-private partnership for the development of malaria vaccines, with national and international agencies sharing the goals, should speed this process as much as possible and boost innovations." They predicted that the RTS,S/AS02A vaccine might be licensed by 2010 if further trials continued to show good results.(London Susan Mayor)