Explained: How Mosquirix vaccine will be the potential game changer in fight against Malaria?

New Delhi, Apr 25: World Malaria Day 2022 will be marked under the theme "Harness innovation to reduce the malaria disease burden and save lives." No single tool that is available today will solve the problem of malaria.

The World Health Organization recommends the expanded use of the first malaria vaccine, calling it a potential game changer in the fight against malaria. It should be noted that to date, no vaccine against malaria has been licensed for use.

What is RTS,S/AS01 Vaccine or Malaria vaccine

A malaria vaccine is a vaccine that is used to prevent malaria. The only approved vaccine, as of 2021, is RTS, S, known by the brand name Mosquirix. In October 2021, the WHO for the first time recommended the large-scale use of a malaria vaccine for children living in areas with moderate-to-high malaria transmission. Four injections are required for full protection.

RTS,S Development

More than a dozen vaccine candidates are now in clinical development, and one, GlaxoSmithKline Biologicals' RTS,S/AS01, completed Phase III clinical testing, and on October 6, 2021, following a large scale pilot implementation, became the first malaria vaccine to receive a WHO recommendation for widespread use among children living in areas of moderate to high malaria transmission.

The vaccine has been in development since the mid-1980s and has advanced thanks to a unique public-private partnership of GSKBio, the PATH Malaria Vaccine Initiative, and African and other research organizations, with funding support from the Bill and Melinda Gates Foundation.

From 2009-2011, children ages 6-12 weeks and 5-17 months were enrolled in the trial at 11 sites in seven African countries. CDC, in collaboration with the Kenya Medical Research Institute, led the trial at one site in western Kenya.

The trial's final results, made available in 2015 external icon, were a promising advance in development of a malaria vaccine for African children.

The RTS,S vaccine reduced clinical and severe cases of malaria by about one-third in 5-17-month-old children over four years who received the three-dose vaccine series plus a booster dose. The vaccine was less effective in children in the young infant group. The vaccine was generally found to be safe, but there were a few safety signals that warranted further study, including febrile convulsions, meningitis, and cerebral malaria.

Notably, the vaccine provided this protection in settings with ongoing use of other effective malaria prevention and treatment interventions: bed nets, antimalarial drugs for disease treatment, indoor residual insecticide spraying to prevent mosquito-borne transmission, and drugs to protect pregnant women and their newborns from malaria's adverse effects.

In July 2015, the European Medicines Agency (EMA) gave a positive regulatory assessment of the RTS,S/AS01 vaccine for 5-17-month-olds, but WHO recommended in October 2015 that the vaccine be further evaluated in large-scale pilot studies before recommending it. Large-scale pilots of the vaccine began in Ghana, Kenya, and Malawi in 2019, including several hundreds of thousands of infants. CDC, in collaboration with KEMRI and several other organizations, is leading the evaluation of the large-scale RTS,S/AS01 pilot in western Kenya. The goal of these pilot evaluations is to assess the feasibility of delivering the three-dose vaccine series plus booster through routine health systems, carefully examine the relationship of the vaccine to specific adverse events (febrile seizures, meningitis, cerebral malaria), and also evaluate its impact on all-cause mortality. CDC, in collaboration with KEMRI and several other organizations, will lead the evaluation of the large-scale RTS,S/AS01 pilot in western Kenya.

While the pilots are still on-going until 2023, sufficient data on safety and efficacy have been collected to allow for a broader recommendation for the use of the vaccine to take place.