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Malaria Vax Yields Promising Results

Data from the Phase III trial of a malaria vaccine breeds hope for immunization as a possible weapon against the dreaded disease.

By | October 18, 2011

image: Malaria Vax Yields Promising Results A 9-month-old Ethiopian child recieving a measels vaccinationWikimedia, Pete Lewis / DFID

A 9-month-old Ethiopian child recieving a measels vaccination WIKIMEDIA, PETE LEWIS / DFID

An experimental vaccine reduced the risk of developing malaria by about 50 percent in 6,000 sub-Saharan African children when combined with existing interventions, such as the use of insecticide-treated bed nets, according to a new study published online today by the New England Journal of Medicine.

Officials and researchers collaborating on the project announced preliminary results from the Phase III clinical trial of the RTS,S malaria vaccine today (18 October) at a malaria meeting in Seattle. "We're on track to make history with this vaccine trial," Christopher Elias, president and CEO of the Seattle-based nonprofit PATH organization, which collaborated in the trial, said during the news conference.

Doctors at 11 sites spread across seven African nations administered three successive doses of the RTS,S vaccine to 6,000 children, aged 5-17 months. Monitoring the patients for up to 12 months the researchers found that the children were 56 percent less likely to experience clinical symptoms of malaria, and 47 percent less likely to develop severe symptoms of the disease.

The RTS,S vaccine, created in the late 1980s by researchers in pharmaceutical giant GSK's Biologicals division, uses a protein from an existing hepatitis B vaccine to fuse a surface protein, called circumsporozoite, from the malaria parasite that helps it invade human liver cells, where it matures, reproduces, and launches its attack on the body's red blood cells. GSK's proprietary adjuvant mixture strengthens the immune response provoked by the vaccine. Partners in the trial, which began in 2009, include the PATH Malaria Vaccine Initiative, the Bill and Melinda Gates Foundation, the Walter Reed Army Institute of Research, and several African research centers.

The results announced today support data from the Phase II efficacy trial published earlier this year in Lancet Infectious Diseases. "Today this collaboration is bearing more sweet fruit in the form of hard data," said Elias.

The RTS,S vaccine trial continues in Africa, with results in the crucial 6-12-week-old infant age group expected by the end of 2012, and long-term efficacy data for all of the study's 15,460 participants expected by the end of 2014. According to GSK CEO Andrew Witty, the vaccine could garner approval by appropriate regulatory authorities and a recommendation from the World Health Organization by 2015.

Witty added that GSK would strive to make the vaccine as affordable as possible, contributing an estimated $50-100 on top of the $300 million already spent on the project to make the RTS,S vaccine, which does require refrigeration in transit, available to African children on a wide scale. “These data bring us to the cusp of having the world’s first malaria vaccine, which has the potential to significantly improve the outlook for children living in malaria endemic regions across Africa," he said during today's conference.

The RTS,S Clinical Trials Partnership, "First Results of Phase 3 Trial of RTS,S/AS01 Malaria Vaccine in African Children," NEJM, 10.1056/NEJMoa1102287, 2011.

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Avatar of: rvspawaiya

rvspawaiya

Posts: 6

October 19, 2011

The 50% reduction in the risk of developing malaria  by this vaccine in 6,000 sub-Saharan African children when combined with existing interventions, such as the use of insecticide-treated bed nets and use of mosqueto repelents, are not very encouraging results. Had the study put proper control, that is, a group with just insecticide-treated bed nets without vaccine and a group with none? I believe that if used properly and regularly, a group with just insecticide-treated bed nets and use of mosqueto repelents will also fare at the same level (50% reduction) as this vaccine is doing in combination with nets.

Avatar of: Brian Hanley

Brian Hanley

Posts: 66

October 19, 2011

An excellent question. The journalist should have cited this study for comparison.

Stephen S. Lim, Nancy Fullman, Andrew Stokes, Nirmala Ravishankar, Felix Masiye, Christopher J. L. Murray, Emmanuela Gakidou. Net
Benefits: A Multicountry Analysis of Observational Data Examining
Associations between Insecticide-Treated Mosquito Nets and Health
Outcomes. PLoS Medicine, 2011; 8 (9): e1001091 DOI: 10.1371/journal.pmed.1001091

"... The pooled relative reduction in parasitemia prevalence from random
effects meta-analysis associated with household ownership of at least
one ITN was 20%."
"... Sleeping under an ITN was associated with a pooled relative reduction in parasitemia prevalence in children of 24%."
"... Ownership of at least one ITN was associated with a pooled relative
reduction in mortality between 1 month and 5 years of age of 23%."
"Our findings across a number of sub-Saharan African countries were
highly consistent with results from previous clinical trials."

These figures suggest that, standalone, the vaccine's efficacy is in the range of 25% - 30%.

The problem with your control suggestion is that it is not ethical to remove, or to not supply, a known intervention that works for a deadly disease when testing something that is not known to be highly efficacious. The study designers did the right thing.

Avatar of:

Posts: 0

October 19, 2011

The 50% reduction in the risk of developing malaria  by this vaccine in 6,000 sub-Saharan African children when combined with existing interventions, such as the use of insecticide-treated bed nets and use of mosqueto repelents, are not very encouraging results. Had the study put proper control, that is, a group with just insecticide-treated bed nets without vaccine and a group with none? I believe that if used properly and regularly, a group with just insecticide-treated bed nets and use of mosqueto repelents will also fare at the same level (50% reduction) as this vaccine is doing in combination with nets.

Avatar of:

Posts: 0

October 19, 2011

An excellent question. The journalist should have cited this study for comparison.

Stephen S. Lim, Nancy Fullman, Andrew Stokes, Nirmala Ravishankar, Felix Masiye, Christopher J. L. Murray, Emmanuela Gakidou. Net
Benefits: A Multicountry Analysis of Observational Data Examining
Associations between Insecticide-Treated Mosquito Nets and Health
Outcomes. PLoS Medicine, 2011; 8 (9): e1001091 DOI: 10.1371/journal.pmed.1001091

"... The pooled relative reduction in parasitemia prevalence from random
effects meta-analysis associated with household ownership of at least
one ITN was 20%."
"... Sleeping under an ITN was associated with a pooled relative reduction in parasitemia prevalence in children of 24%."
"... Ownership of at least one ITN was associated with a pooled relative
reduction in mortality between 1 month and 5 years of age of 23%."
"Our findings across a number of sub-Saharan African countries were
highly consistent with results from previous clinical trials."

These figures suggest that, standalone, the vaccine's efficacy is in the range of 25% - 30%.

The problem with your control suggestion is that it is not ethical to remove, or to not supply, a known intervention that works for a deadly disease when testing something that is not known to be highly efficacious. The study designers did the right thing.

Avatar of:

Posts: 0

October 19, 2011

The 50% reduction in the risk of developing malaria  by this vaccine in 6,000 sub-Saharan African children when combined with existing interventions, such as the use of insecticide-treated bed nets and use of mosqueto repelents, are not very encouraging results. Had the study put proper control, that is, a group with just insecticide-treated bed nets without vaccine and a group with none? I believe that if used properly and regularly, a group with just insecticide-treated bed nets and use of mosqueto repelents will also fare at the same level (50% reduction) as this vaccine is doing in combination with nets.

Avatar of:

Posts: 0

October 19, 2011

An excellent question. The journalist should have cited this study for comparison.

Stephen S. Lim, Nancy Fullman, Andrew Stokes, Nirmala Ravishankar, Felix Masiye, Christopher J. L. Murray, Emmanuela Gakidou. Net
Benefits: A Multicountry Analysis of Observational Data Examining
Associations between Insecticide-Treated Mosquito Nets and Health
Outcomes. PLoS Medicine, 2011; 8 (9): e1001091 DOI: 10.1371/journal.pmed.1001091

"... The pooled relative reduction in parasitemia prevalence from random
effects meta-analysis associated with household ownership of at least
one ITN was 20%."
"... Sleeping under an ITN was associated with a pooled relative reduction in parasitemia prevalence in children of 24%."
"... Ownership of at least one ITN was associated with a pooled relative
reduction in mortality between 1 month and 5 years of age of 23%."
"Our findings across a number of sub-Saharan African countries were
highly consistent with results from previous clinical trials."

These figures suggest that, standalone, the vaccine's efficacy is in the range of 25% - 30%.

The problem with your control suggestion is that it is not ethical to remove, or to not supply, a known intervention that works for a deadly disease when testing something that is not known to be highly efficacious. The study designers did the right thing.

Avatar of:

Posts: 0

October 22, 2011

Thanks Brian for your nice explanation. 
I have read the article suggested by you and agree with your estimate that effective vaccine's efficacy is in the range of 25%-30%. I also agree with that ethical issue for using control with no ITN. These things are not actually possible when human beings are involved in the study. So all-in-all, a partially efective vaccine but a significant step towards malaria prophylaxis nonetheless.

Avatar of:

Posts: 0

October 22, 2011

Thanks Brian for your nice explanation. 
I have read the article suggested by you and agree with your estimate that effective vaccine's efficacy is in the range of 25%-30%. I also agree with that ethical issue for using control with no ITN. These things are not actually possible when human beings are involved in the study. So all-in-all, a partially efective vaccine but a significant step towards malaria prophylaxis nonetheless.

Avatar of: rvspawaiya

rvspawaiya

Posts: 6

October 22, 2011

Thanks Brian for your nice explanation. 
I have read the article suggested by you and agree with your estimate that effective vaccine's efficacy is in the range of 25%-30%. I also agree with that ethical issue for using control with no ITN. These things are not actually possible when human beings are involved in the study. So all-in-all, a partially efective vaccine but a significant step towards malaria prophylaxis nonetheless.

October 26, 2011

First of all, "circumsporozoite" is not "a surface protein," it's a whole organism (a developmental stage of the parasite).  Doesn't Bob Grant realize that most of the readers of his articles are themselves scientists? 

Second of all, rvspawaiya is absolutely correct in writing that these are NOT very encouraging results. 

There are potentially far far better vaccine candidates out there, some of which take into account various critical issues concerning the biology of the parasite and the host-parasite relationship that can make-or-break a vaccine's effectiveness, and some of these have been published in reputable peer-reviewed journals.  The idea that a single surface protein from the circumsporozoite can be a highly effective vaccine flies in the face of common sense to anyone who is familiar with the biology of this disease.  In order for a vaccine to be effective, it must "address" multiple stages of the parasite in the human host, and it must address the uncanny ability of the parasite proteins to escape human immune surveillance.  Mere fusion of a single parasite protein to an intrinsically immunogenic protein ain't gonna work, and selecting only one protein, and at that a protein that is not present on the blood-borne form of the parasite, ain't gonna work either.   

Avatar of: TheSciAdmin

TheSciAdmin

Posts: 56

October 26, 2011

Hello Retired,

Thanks for reading The Scientist. And thanks for catching my mistake. I've fixed it in the story and published a correction that you can see above. As for the validity of the study and/or the effectiveness of the vaccine...I'll let that discussion play out here in the comments and in the wider scientific community.

Thanks again,

Bob Grant

October 26, 2011

There is a missing control which would not have been unethical:  the hepatitis B vaccine protein all by itself, in conjunction with the "existing interventions" as would of course be ethically required.

Another point -- would even this "not very encouraging" but better-than-nothing vaccine be appropriate for infants or young children?  The youngsters are at greatest risk from this disease; adults with the disease (i.e., those in endemic regions who have survived previous infections and are once again re-infected) are at far less risk of dying than are the youngsters. 

Avatar of:

Posts: 0

October 26, 2011

First of all, "circumsporozoite" is not "a surface protein," it's a whole organism (a developmental stage of the parasite).  Doesn't Bob Grant realize that most of the readers of his articles are themselves scientists? 

Second of all, rvspawaiya is absolutely correct in writing that these are NOT very encouraging results. 

There are potentially far far better vaccine candidates out there, some of which take into account various critical issues concerning the biology of the parasite and the host-parasite relationship that can make-or-break a vaccine's effectiveness, and some of these have been published in reputable peer-reviewed journals.  The idea that a single surface protein from the circumsporozoite can be a highly effective vaccine flies in the face of common sense to anyone who is familiar with the biology of this disease.  In order for a vaccine to be effective, it must "address" multiple stages of the parasite in the human host, and it must address the uncanny ability of the parasite proteins to escape human immune surveillance.  Mere fusion of a single parasite protein to an intrinsically immunogenic protein ain't gonna work, and selecting only one protein, and at that a protein that is not present on the blood-borne form of the parasite, ain't gonna work either.   

Avatar of:

Posts: 0

October 26, 2011

Hello Retired,

Thanks for reading The Scientist. And thanks for catching my mistake. I've fixed it in the story and published a correction that you can see above. As for the validity of the study and/or the effectiveness of the vaccine...I'll let that discussion play out here in the comments and in the wider scientific community.

Thanks again,

Bob Grant

Avatar of:

Posts: 0

October 26, 2011

There is a missing control which would not have been unethical:  the hepatitis B vaccine protein all by itself, in conjunction with the "existing interventions" as would of course be ethically required.

Another point -- would even this "not very encouraging" but better-than-nothing vaccine be appropriate for infants or young children?  The youngsters are at greatest risk from this disease; adults with the disease (i.e., those in endemic regions who have survived previous infections and are once again re-infected) are at far less risk of dying than are the youngsters. 

Avatar of:

Posts: 0

October 26, 2011

First of all, "circumsporozoite" is not "a surface protein," it's a whole organism (a developmental stage of the parasite).  Doesn't Bob Grant realize that most of the readers of his articles are themselves scientists? 

Second of all, rvspawaiya is absolutely correct in writing that these are NOT very encouraging results. 

There are potentially far far better vaccine candidates out there, some of which take into account various critical issues concerning the biology of the parasite and the host-parasite relationship that can make-or-break a vaccine's effectiveness, and some of these have been published in reputable peer-reviewed journals.  The idea that a single surface protein from the circumsporozoite can be a highly effective vaccine flies in the face of common sense to anyone who is familiar with the biology of this disease.  In order for a vaccine to be effective, it must "address" multiple stages of the parasite in the human host, and it must address the uncanny ability of the parasite proteins to escape human immune surveillance.  Mere fusion of a single parasite protein to an intrinsically immunogenic protein ain't gonna work, and selecting only one protein, and at that a protein that is not present on the blood-borne form of the parasite, ain't gonna work either.   

Avatar of:

Posts: 0

October 26, 2011

Hello Retired,

Thanks for reading The Scientist. And thanks for catching my mistake. I've fixed it in the story and published a correction that you can see above. As for the validity of the study and/or the effectiveness of the vaccine...I'll let that discussion play out here in the comments and in the wider scientific community.

Thanks again,

Bob Grant

Avatar of:

Posts: 0

October 26, 2011

There is a missing control which would not have been unethical:  the hepatitis B vaccine protein all by itself, in conjunction with the "existing interventions" as would of course be ethically required.

Another point -- would even this "not very encouraging" but better-than-nothing vaccine be appropriate for infants or young children?  The youngsters are at greatest risk from this disease; adults with the disease (i.e., those in endemic regions who have survived previous infections and are once again re-infected) are at far less risk of dying than are the youngsters. 

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