RTS,S
RTS, S with its trade name Mosquirix is the first licensed malaria vaccine in the world, it is also the first vaccine licensed for use against a parasitic disease of any kind. It has been funded in part by the PATH Malaria Vaccine Initiative and the Bill and Melinda Gates Foundation. Its efficacy ranges from 26 to 50% in infants and young children. It is considered to be a milestone advance in the worldwide campaign against malaria. On 23 October 2015, The World Health Organization’s Strategic Advisory Group of Experts on Immunization (SAGE) and the Malaria Policy Advisory Committee (MPAC) jointly recommended a pilot implementation of the vaccine in Africa. It was then approved by the European Regulators in June 2015.
The RTS, S vaccine was conceived of and created in the late 1980s by scientists working at SmithKline Beecham Biologicals (now GlaxoSmithKline Vaccines) laboratories in Belgium. The vaccine was further developed through collaboration between GSK and the Walter Reed Army Institute of Research. In November 2012, findings from a Phase III trial of RTS,S reported that it provided modest protection against both clinical and severe malaria in young infants. In October 2013, GlaxoSmithKline (GSK) reported that the RTS,S vaccine reduced the amount of cases amongst young children by almost 50 percent and among infants by around 25 percent, following the conclusion of an 18-month clinical trial. Data showed the protective effect after the 18 months, however, was less than had previously been seen after 12 months. The EMA approved the RTS,S vaccine in July 2015, with a recommendation that it be used in Africa for babies at risk of getting malaria. After additional regulatory decisions by the World Health Organization, and individual African country governments, a roll out of the product could come as early as 2017. Vaccinations are due to begin in 2018 in the three sub-Saharan countries where it first will be rolled out.
The RTS,S vaccine was engineered using genes from the repeat and T-cell epitope in the pre-erythrocytic circumsporozoite protein (CSP) of the Plasmodium falciparum malaria parasite and a viral envelope protein of the hepatitis B virus (HBsAg), to which was added a chemical adjuvant (AS01) to increase the immune system response. Infection is prevented by inducing humoral and cellular immunity, with high antibody titers, that block the parasite from infecting the liver. RTS,S is an injectable vaccine that provides partial protection against malaria in young children. Like vaccines generally, RTS,S aims to trigger the body’s own immune system to defend against disease, in this case, malaria caused by Plasmodium falciparum, the most deadly species of the malaria parasite globally and the most prevalent in Africa. The large-scale Phase 3 efficacy and safety trial of RTS,S (which concluded in January 2014) showed that the vaccine candidate could provide meaningful public health benefit by reducing the burden of malaria when used alongside currently available interventions such as bednets and insecticides.
RTS,S/AS01 prevented a substantial number of cases of clinical malaria over a 3–4 year period in young infants and children when administered with or without a booster dose. Efficacy was enhanced by the administration of a booster dose in both age categories. Thus, the vaccine has the potential to make a substantial contribution to malaria control when used in combination with other effective control measures, especially in areas of high transmission.
