Introduction
- Represent critical milestones in combating Plasmodium falciparum infections globally.
- Target pre-erythrocytic stage specifically.
- Prevent parasite from establishing initial hepatic infection.
- Confer maximum impact when combined with seasonal malaria chemoprevention and insecticide-treated bed nets.
- Save child lives and significantly reduce all-cause mortality in endemic areas.
Approved Vaccines
RTS,S/AS01 Vaccine
- First vaccine recommended for human parasitic disease by World Health Organization.
- Recombinant fusion protein based on repeat sequence of circumsporozoite protein antigen.
- Expressed on surface of P. falciparum sporozoites.
- Contains S antigen derived from hepatitis B surface antigen.
- Utilizes proprietary AS01 liquid adjuvant.
- Demonstrates over 50% reduction in clinical malaria cases during first 12 months post-vaccination.
- Efficacy declines rapidly over time without timely booster doses.
R21/Matrix-M Vaccine
- Recommended by World Health Organization in 2023.
- Virus-like protein based on circumsporozoite protein from P. falciparum strain NF54.
- Fused directly to N-terminus of hepatitis B surface antigen.
- Utilizes Matrix-M proprietary adjuvant.
- Shows 71-76% efficacy against clinical malaria episodes over 12 months.
- Prevents nearly 75% of cases when administered prior to rainy season in highly seasonal transmission areas.
Immunization Schedule
- Target population includes children living in moderate to high transmission regions.
- Four-dose primary schedule initiated around 5 months of age.
- First three doses administered at 4-week intervals.
- Fourth dose administered 12 to 18 months following third dose.
- Fifth booster dose considered 1 year after fourth dose in high-risk zones.
Safety Profile
- Both approved vaccines demonstrate favorable safety profiles.
- Common adverse reactions include fever, irritability, and injection site pain.
- Febrile seizures occur rarely within 7 days post-vaccination.
- Well tolerated in premature, low birth weight, malnourished, and human immunodeficiency virus-infected children.
Multi-Stage Vaccines
- Second Generation Malaria Vaccine Consortium developing candidates targeting multiple parasite lifecycle stages simultaneously.
- Combines R21 antigen with blood-stage antigens RH5.1 and R78C.
- Targets RIPR and CyRPA antigens to block red blood cell invasion by merozoites.
- Aims for stronger, longer-lasting protection and significantly reduced disease transmission.
- BioNTech developing BNT165e investigational candidate.
- Multi-antigen ribonucleic acid-based vaccine encapsulated in lipid nanoparticles.
- Encodes full-length circumsporozoite protein alongside conserved liver-stage proteins.
- Broadens immune response to overcome genetic diversity causing vaccine escape.
Monoclonal Antibodies
- L9LS targets P. falciparum sporozoites via subcutaneous administration.
- Reduces infection frequency by 70% compared to placebo in phase 2 trials.
- CIS43LS represents another monoclonal antibody targeting sporozoite circumsporozoite protein undergoing clinical evaluation.