Posted on Apr 17, 2019, 4 p.m.
Promising malaria vaccine PfSPZ is to be tested in the first large scale field trial, which is hoped to confer up to 100% protection in this testing involving 2,100 people residing on the West African island of Bioko to study efficacy under real world conditions, as published in Nature.
To begin early 2020 on Bioko island off the coast of Equatorial Guinea this trial which is needed to provide efficacy and safety data required for regulatory approval will involve 2,100 people between the ages of 2-50 and is sponsored by Equatorial Guinea’s government and private energy companies.
The malaria vaccine PfSPZ has proven to be the most effective developed so far giving healthy volunteers complete protection in laboratory testing by eliciting an immune response against the malaria parasite Plasmodium falciparum. Made of sporozoites that infected mosquitoes injected into people during a bite, sanaria isolates and purifies billions of sporozoites from farmed mosquitoes.
This vaccine candidate is unique in that it uses whole parasites ingredients, while most others include only a small number of genetically engineered parasite proteins; this abundance of proteins in the whole parasite vaccine may explain why it is so successful in provoking such a strong immune response.
This vaccine may pose a challenge to mass vaccination campaigns as it is a more complex procedure requiring to be injected intravenously. However the difficulties this presents are thought to be surmountable according to Hoffman.
The population of Bioko island is around 280,000 people and is a region where malaria occurs. The efficacy of PfSPZ will inevitably be lower than the lab studies using healthy people as those who have already has malaria are likely to have weaker immune responses, and local strains of the malaria parasite will also differ from the one used in the vaccine explains Stefan Kappe. A reasonably effective vaccine may still have a big impact, prevalence of malaria in Bioko has dropped to 12.5% from 45% in 15 years through conventional measures such as insecticide spraying, getting to zero may be a difficult journey that may be aided with this vaccine. “This trial will be answering several questions for the first time, including whether a vaccine can completely eliminate malaria from this island environment,” says Kappe.
If successful another larger trail will be carried out on the island involving 10,000 people to compare disease levels between communities that get the vaccine in addition to using standard conventional malaria prevention measures with levels in control communities not getting the vaccine according to Hoffman. Efficacy of the vaccine in the subsequent larger trial is expected to be higher because of herd immunity; if successful the vaccine is then planned to be rolled out to the entire island population to assess effectiveness.
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