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The malaria vaccine candidate RTS,S/AS01 (Mosquirix) could have a significant impact on public health in a range of settings across sub-Saharan Africa, according to mathematical models.
Researchers found that, over a 15-year time horizon, an average of 116,500 cases of clinical malaria and 484 malaria deaths would be averted for every 100,000 children vaccinated under a 4-dose schedule of immunizations at 6, 7.5, 9, and 27 months of age.
This translates to approximately 1.2 malaria cases averted per vaccinated child and 1 malaria death averted for every 200 children vaccinated.
These data apply to children living in regions of Africa that experience moderate to high malaria transmission—countries where prevalence rates for the malaria parasite Plasmodium falciparum range from 10% to 65%—and assumes a vaccine coverage rate at the fourth dose of approximately 70%.
The findings, published in The Lancet, contribute to the scientific evidence being considered by the World Health Organization, which is assessing the vaccine candidate for use in Africa.
“We took a realistic look at expected coverage of the RTS,S vaccine in a variety of African settings and found it would have significant impact on malaria disease in all but the lowest malaria transmission regions,” said Melissa Penny, PhD, of the Swiss Tropical and Public Health Institute in Basel.
“Our numbers indicate that 6% to 29% of malaria deaths in children younger than age 5 could potentially be averted by the vaccine in the areas in which it is implemented, when used alongside other malaria control interventions.”
This is the first modeling study to use final, site-specific results of the RTS,S phase 3 safety and efficacy trial coordinated by GlaxoSmithKline and conducted at 11 sites in 7 African countries. And it accounts for implementation of the vaccine alongside use of long-lasting, insecticide-treated bed nets.
There was consensus across the predictions from all 4 groups that took part in the study. The participating institutions are Imperial College London in the UK, Swiss Tropical and Public Health Institute, the Institute for Disease Modeling in the US, and GlaxoSmithKline in Belgium.
According to the study authors, public health authorities require these types of impact estimates on malaria disease and deaths to inform vaccine implementation.
Models can account for differences between the trial and real-life settings in transmission levels and healthcare accessibility, as well as predict RTS,S’s impact on malaria mortality, which was not possible to assess in the trial.
Cost-effectiveness
As part of the modeling study, the researchers considered a range of possible prices for RTS,S, from $2 to $10. They found that, compared to current malaria interventions, the vaccine would be cost-effective to implement under an assumed price of USD$5 per dose in areas of moderate and high malaria transmission.
”The cost-effectiveness of RTS,S is similar to what we’ve seen for other recently introduced childhood vaccines,” said Azra Ghani, PhD, of Imperial College London.
“It also overlaps within the ranges of cost-effectiveness of other malaria control interventions like bed nets and indoor residual sprays. However, it is important that the vaccine is introduced in addition to these other highly cost-effective interventions.”
The researchers measured cost-effectiveness in terms of disability-adjusted life years (DALYs), a metric used by health economists to compare the impacts of health interventions in populations over time. One DALY is equivalent to 1 lost year of healthy life. The lower the amount spent per DALY averted, the greater the cost-effectiveness of an intervention.
With the vaccine priced at $5 per dose, the researchers estimated a median cost of $87 per DALY averted for a 4-dose vaccine schedule across the range of transmission settings with parasite prevalence 10% to 65%.
This cost was estimated to vary depending on the level of malaria transmission found in a particular location—with the vaccine being increasingly cost-effective in areas with a higher malaria burden.
The researchers noted that, according to earlier studies, the cost per DALY averted for other malaria interventions indicate averages of $27 for long-lasting, insecticide-treated bed nets; $143 for indoor residual spraying; and $24 for intermittent preventative treatment.
Caveats
The researchers conceded that this study has its limitations. One is the remaining uncertainty regarding the vaccine’s efficacy after the 4 years of follow-up observed in the phase 3 trial.
The team also noted that, since the phase 3 trial of RTS,S was not large enough to test for a reduction in deaths from malaria (versus reduction in incidence of malaria cases) and the quality of care provided to participants was high, the modeling studies’ projection of deaths requires further validation during the implementation phase.
“It will be important to continue to track the long-term impact of this vaccine to ensure that the effectiveness predicted by the models is borne out in practice,” said Caitlin Bever, PhD, of the Institute for Disease Modeling in Bellevue, Washington. 
Photo by Caitlin Kleiboer
The malaria vaccine candidate RTS,S/AS01 (Mosquirix) could have a significant impact on public health in a range of settings across sub-Saharan Africa, according to mathematical models.
Researchers found that, over a 15-year time horizon, an average of 116,500 cases of clinical malaria and 484 malaria deaths would be averted for every 100,000 children vaccinated under a 4-dose schedule of immunizations at 6, 7.5, 9, and 27 months of age.
This translates to approximately 1.2 malaria cases averted per vaccinated child and 1 malaria death averted for every 200 children vaccinated.
These data apply to children living in regions of Africa that experience moderate to high malaria transmission—countries where prevalence rates for the malaria parasite Plasmodium falciparum range from 10% to 65%—and assumes a vaccine coverage rate at the fourth dose of approximately 70%.
The findings, published in The Lancet, contribute to the scientific evidence being considered by the World Health Organization, which is assessing the vaccine candidate for use in Africa.
“We took a realistic look at expected coverage of the RTS,S vaccine in a variety of African settings and found it would have significant impact on malaria disease in all but the lowest malaria transmission regions,” said Melissa Penny, PhD, of the Swiss Tropical and Public Health Institute in Basel.
“Our numbers indicate that 6% to 29% of malaria deaths in children younger than age 5 could potentially be averted by the vaccine in the areas in which it is implemented, when used alongside other malaria control interventions.”
This is the first modeling study to use final, site-specific results of the RTS,S phase 3 safety and efficacy trial coordinated by GlaxoSmithKline and conducted at 11 sites in 7 African countries. And it accounts for implementation of the vaccine alongside use of long-lasting, insecticide-treated bed nets.
There was consensus across the predictions from all 4 groups that took part in the study. The participating institutions are Imperial College London in the UK, Swiss Tropical and Public Health Institute, the Institute for Disease Modeling in the US, and GlaxoSmithKline in Belgium.
According to the study authors, public health authorities require these types of impact estimates on malaria disease and deaths to inform vaccine implementation.
Models can account for differences between the trial and real-life settings in transmission levels and healthcare accessibility, as well as predict RTS,S’s impact on malaria mortality, which was not possible to assess in the trial.
Cost-effectiveness
As part of the modeling study, the researchers considered a range of possible prices for RTS,S, from $2 to $10. They found that, compared to current malaria interventions, the vaccine would be cost-effective to implement under an assumed price of USD$5 per dose in areas of moderate and high malaria transmission.
”The cost-effectiveness of RTS,S is similar to what we’ve seen for other recently introduced childhood vaccines,” said Azra Ghani, PhD, of Imperial College London.
“It also overlaps within the ranges of cost-effectiveness of other malaria control interventions like bed nets and indoor residual sprays. However, it is important that the vaccine is introduced in addition to these other highly cost-effective interventions.”
The researchers measured cost-effectiveness in terms of disability-adjusted life years (DALYs), a metric used by health economists to compare the impacts of health interventions in populations over time. One DALY is equivalent to 1 lost year of healthy life. The lower the amount spent per DALY averted, the greater the cost-effectiveness of an intervention.
With the vaccine priced at $5 per dose, the researchers estimated a median cost of $87 per DALY averted for a 4-dose vaccine schedule across the range of transmission settings with parasite prevalence 10% to 65%.
This cost was estimated to vary depending on the level of malaria transmission found in a particular location—with the vaccine being increasingly cost-effective in areas with a higher malaria burden.
The researchers noted that, according to earlier studies, the cost per DALY averted for other malaria interventions indicate averages of $27 for long-lasting, insecticide-treated bed nets; $143 for indoor residual spraying; and $24 for intermittent preventative treatment.
Caveats
The researchers conceded that this study has its limitations. One is the remaining uncertainty regarding the vaccine’s efficacy after the 4 years of follow-up observed in the phase 3 trial.
The team also noted that, since the phase 3 trial of RTS,S was not large enough to test for a reduction in deaths from malaria (versus reduction in incidence of malaria cases) and the quality of care provided to participants was high, the modeling studies’ projection of deaths requires further validation during the implementation phase.
“It will be important to continue to track the long-term impact of this vaccine to ensure that the effectiveness predicted by the models is borne out in practice,” said Caitlin Bever, PhD, of the Institute for Disease Modeling in Bellevue, Washington.
Photo by Caitlin Kleiboer
The malaria vaccine candidate RTS,S/AS01 (Mosquirix) could have a significant impact on public health in a range of settings across sub-Saharan Africa, according to mathematical models.
Researchers found that, over a 15-year time horizon, an average of 116,500 cases of clinical malaria and 484 malaria deaths would be averted for every 100,000 children vaccinated under a 4-dose schedule of immunizations at 6, 7.5, 9, and 27 months of age.
This translates to approximately 1.2 malaria cases averted per vaccinated child and 1 malaria death averted for every 200 children vaccinated.
These data apply to children living in regions of Africa that experience moderate to high malaria transmission—countries where prevalence rates for the malaria parasite Plasmodium falciparum range from 10% to 65%—and assumes a vaccine coverage rate at the fourth dose of approximately 70%.
The findings, published in The Lancet, contribute to the scientific evidence being considered by the World Health Organization, which is assessing the vaccine candidate for use in Africa.
“We took a realistic look at expected coverage of the RTS,S vaccine in a variety of African settings and found it would have significant impact on malaria disease in all but the lowest malaria transmission regions,” said Melissa Penny, PhD, of the Swiss Tropical and Public Health Institute in Basel.
“Our numbers indicate that 6% to 29% of malaria deaths in children younger than age 5 could potentially be averted by the vaccine in the areas in which it is implemented, when used alongside other malaria control interventions.”
This is the first modeling study to use final, site-specific results of the RTS,S phase 3 safety and efficacy trial coordinated by GlaxoSmithKline and conducted at 11 sites in 7 African countries. And it accounts for implementation of the vaccine alongside use of long-lasting, insecticide-treated bed nets.
There was consensus across the predictions from all 4 groups that took part in the study. The participating institutions are Imperial College London in the UK, Swiss Tropical and Public Health Institute, the Institute for Disease Modeling in the US, and GlaxoSmithKline in Belgium.
According to the study authors, public health authorities require these types of impact estimates on malaria disease and deaths to inform vaccine implementation.
Models can account for differences between the trial and real-life settings in transmission levels and healthcare accessibility, as well as predict RTS,S’s impact on malaria mortality, which was not possible to assess in the trial.
Cost-effectiveness
As part of the modeling study, the researchers considered a range of possible prices for RTS,S, from $2 to $10. They found that, compared to current malaria interventions, the vaccine would be cost-effective to implement under an assumed price of USD$5 per dose in areas of moderate and high malaria transmission.
”The cost-effectiveness of RTS,S is similar to what we’ve seen for other recently introduced childhood vaccines,” said Azra Ghani, PhD, of Imperial College London.
“It also overlaps within the ranges of cost-effectiveness of other malaria control interventions like bed nets and indoor residual sprays. However, it is important that the vaccine is introduced in addition to these other highly cost-effective interventions.”
The researchers measured cost-effectiveness in terms of disability-adjusted life years (DALYs), a metric used by health economists to compare the impacts of health interventions in populations over time. One DALY is equivalent to 1 lost year of healthy life. The lower the amount spent per DALY averted, the greater the cost-effectiveness of an intervention.
With the vaccine priced at $5 per dose, the researchers estimated a median cost of $87 per DALY averted for a 4-dose vaccine schedule across the range of transmission settings with parasite prevalence 10% to 65%.
This cost was estimated to vary depending on the level of malaria transmission found in a particular location—with the vaccine being increasingly cost-effective in areas with a higher malaria burden.
The researchers noted that, according to earlier studies, the cost per DALY averted for other malaria interventions indicate averages of $27 for long-lasting, insecticide-treated bed nets; $143 for indoor residual spraying; and $24 for intermittent preventative treatment.
Caveats
The researchers conceded that this study has its limitations. One is the remaining uncertainty regarding the vaccine’s efficacy after the 4 years of follow-up observed in the phase 3 trial.
The team also noted that, since the phase 3 trial of RTS,S was not large enough to test for a reduction in deaths from malaria (versus reduction in incidence of malaria cases) and the quality of care provided to participants was high, the modeling studies’ projection of deaths requires further validation during the implementation phase.
“It will be important to continue to track the long-term impact of this vaccine to ensure that the effectiveness predicted by the models is borne out in practice,” said Caitlin Bever, PhD, of the Institute for Disease Modeling in Bellevue, Washington.