Malaria vaccine
[8] In April 2023, Ghana's Food and Drugs Authority approved the use of the R21 vaccine for use in children aged between five months and three years old.
[4] RTS,S was developed by PATH Malaria Vaccine Initiative (MVI) and GlaxoSmithKline (GSK) with support from the Bill and Melinda Gates Foundation.
RTS,S attempted to avoid these by fusing the protein with a surface antigen from hepatitis B virus, creating a more potent and immunogenic vaccine.
When tested in trials as an emulsion of oil in water and with the added adjuvants of monophosphoryl A and QS21 (SBAS2), the vaccine gave protective immunity to 7 out of 8 volunteers when challenged with P.
[11] RTS,S was engineered using genes from the outer protein of P. falciparum malaria parasite and a portion of a hepatitis B virus plus a chemical adjuvant to boost the immune response.
[12] In November 2012, a Phase III trial of RTS,S found that it provided modest protection against both clinical and severe malaria in young infants.
Three doses of vaccine plus a booster reduced the risk of clinical episodes by 26 percent over three years but offered no significant protection against severe malaria.
[14] In a bid to accommodate a larger group and guarantee sustained availability for the general public, GSK applied for a marketing license with the European Medicines Agency (EMA) in July 2014.
[15] GSK treated the project as a non-profit initiative, with most funding coming from the Gates Foundation, a major contributor to malaria eradication.
[3] In August 2022, UNICEF awarded a contract to GSK to supply 18 million doses of the RTS,S vaccine over three years.
[3] The next 9 countries to receive the vaccine over the next 2 years are Benin, Burkina Faso, Burundi, Cameroon, the Democratic Republic of the Congo, Liberia, Niger, Sierra Leone, and Uganda.
[27] A phase III trial with 4,800 children across four African countries was reported in November 2022, demonstrating vaccine efficacy of 74% against a severe malaria episode.
[9] Ghana's Food and Drugs Authority approved the use of the R21 vaccine in April 2023, for use in children aged between five months to three years old.
[39] It has been subject to some criticism regarding the ultimate feasibility of large-scale production and delivery in Africa since it must be stored in liquid nitrogen.
The Plasmodium species has a very high rate of replication, much higher than that needed to ensure transmission in the parasite's lifecycle.
[citation needed] This enables pharmaceutical treatments that are effective at reducing the reproduction rate, but not halting it, to exert a high selection pressure, thus favoring the development of resistance.
Taking this information into consideration an ideal vaccine candidate would attempt to generate a more substantial cell-mediated and antibody response on parasite presentation.
[citation needed] The epidemiology of malaria varies enormously across the globe and has led to the belief that it may be necessary to adopt very different vaccine development strategies to target different populations.
The distinct developmental stages involved in the lifecycle present numerous opportunities for targeting antigens, thus potentially eliciting an immune response.
Moreover, any vaccine produced would ideally have the ability to be of therapeutic value as well as preventing further transmission and is likely to consist of a combination of antigens from different phases of the parasite's development.
The majority of research into malarial vaccines has focused on the Plasmodium falciparum strain due to the high mortality caused by the parasite and the ease of carrying out in vitro/in vivo studies.
[citation needed] Increasing the potential immunity generated against Plasmodia can be achieved by attempting to target multiple phases in the lifecycle.
