Malaria vaccination issues as elimination becomes possible

Understanding Malaria Transmission

• Malaria was initially believed to be caused by miasma or foul air from swamps.

• Alphonse Laveran identified the Plasmodium parasite in 1880, proving malaria was caused by a living organism.

• The question of how the parasite entered humans remained unanswered until 1897 when Ronald Ross demonstrated that Plasmodium completed its life cycle in mosquitoes.

Understanding Parasites

• Plasmodium’s life cycle is crucial to understanding the difficulty in developing vaccines.

• The parasite’s life cycle begins when an infected Anopheles mosquito bites a human, injecting highly infective Plasmodium sporozoites into the bloodstream.

• The parasite’s greatest strength is antigenic variation, where it frequently changes its surface proteins, making it difficult for immune cells to recognize it and respond.

• Plasmodium’s ability to evade detection weakens the body’s ability to develop long-lasting immunity, making reinfection common.

Malaria Vaccines

• The RTS, S malaria vaccine was the first to receive WHO approval for large-scale rollout in endemic regions after 60 years of research.

• The efficacy of the RTS, S vaccine is limited, reducing malaria cases by approximately 36% after four doses over four years in children.

• Researchers are developing second-generation malaria vaccines, including the R21/Matrix-M vaccine, the PfSPZ vaccine, RH5-based vaccines, and transmission-blocking vaccines.

Research Underfunding

• Malaria vaccine research has long suffered from underfunding due to its primarily low-income countries in Africa and parts of South Asia.

• The complexity of the parasite has discouraged pharmaceutical companies from investing in malaria vaccines due to the high cost of research and uncertain returns on investment.