Can adults receive the malaria vaccine and what is its efficacy in this population?

Malaria Vaccine for Adults: Availability and Efficacy

Currently available malaria vaccines (RTS,S/AS01 and R21/Matrix-M) are not recommended for adult travelers from non-endemic countries and are only approved for children aged 5-17 months in malaria-endemic regions. 1, 2

Current Vaccine Status

Approved Vaccines - Pediatric Use Only

• The WHO recommended RTS,S/AS01 in October 2021 for children aged 5-17 months living in areas of moderate to high malaria transmission 1
• A second vaccine (R21/Matrix-M) received WHO approval in October 2023 for the same pediatric population, demonstrating approximately 70% efficacy in protecting young children for one year 1
• Neither vaccine is commercially available or recommended for adult travelers to endemic countries 1, 2

Why Adults Cannot Receive These Vaccines

• The efficacy of existing malaria vaccines is limited and differs dramatically from other travel medicine vaccines 2
• These vaccines provide only partial protection and are designed as public health tools for endemic populations, not for travelers 1, 3
• No data support their use in malaria-naive adults traveling to endemic areas 2

Adult Efficacy Data - Limited and Insufficient

Historical Adult Studies

• RTS,S/AS02A (predecessor formulation) showed partial protection in hyperimmune adults living in endemic areas, but this does not translate to recommendations for non-immune adult travelers 3
• In African children aged 1-4 years, RTS,S/AS02A demonstrated 35.3% efficacy over 18 months and 48.6% efficacy against severe malaria, but protection waned significantly after the initial 6 months 3
• The durability and magnitude of protection are insufficient to replace standard malaria prevention strategies in adults 3, 4

Current Research Limitations

• Multiple next-generation approaches are in development (radiation-attenuated sporozoites, monoclonal antibodies, self-amplifying RNA vaccines), but none are currently available for clinical use 5, 4
• Fundamental scientific advances in immune response potency, durability, and breadth are still required before vaccines can achieve >50% durable efficacy 4

Recommended Prevention for Adults

Primary Prevention Strategies

• Repellent use is the most important measure to prevent malaria infection in adult travelers 2
• Chemoprophylaxis is strongly advised for high-risk destinations 2
• Standard antimalarial prophylaxis options include chloroquine (for chloroquine-sensitive regions), atovaquone-proguanil, or artemisinin-based combinations depending on resistance patterns 6

Important Timing Considerations

• If chloroquine is needed for malaria prophylaxis and cholera vaccination (Dukoral) is also indicated, start chloroquine ≥10 days after Dukoral vaccination due to reduced immunogenicity when coadministered 7
• Chloroquine can interfere with antibody response to certain vaccines, including rabies vaccine (HDCV), so timing must be carefully coordinated 8

Clinical Bottom Line

Adult travelers must rely on chemoprophylaxis and mosquito avoidance rather than vaccination. The current malaria vaccines are pediatric public health tools with partial efficacy unsuitable for adult travelers. Many fundamental questions in malaria vaccinology remain unanswered, and highly effective vaccines providing sustained protection for adults are not yet available. 1, 5, 2, 4