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Safety and immunogenicity of the RTS,S/AS02A candidate malaria vaccine in children aged 1-4 in Mozambique
E Macete1, J J Aponte, C Guinovart
1Centro de Investigação em Saúde da Manhiça (CISM), Manhiça, Mozambique.
Insights
The RTS,S/AS02A malaria vaccine is safe and well-tolerated in children aged 1-4 in Mozambique. It demonstrated strong immunogenicity, paving the way for larger efficacy studies.
Area of Science:
- * Vaccinology and Tropical Public Health
- * Pediatric Infectious Diseases
Background:
- * Malaria vaccine development is critical for sub-Saharan Africa.
- * RTS,S/AS02A malaria vaccine showed prior safety and immunogenicity in adults and children.
- * Factors like genetics and transmission intensity may influence vaccine response.
Purpose of the Study:
- * To evaluate the safety, reactogenicity, and immunogenicity of the pediatric RTS,S/AS02A vaccine dose in children aged 1-4 in Mozambique.
- * To inform a planned larger phase IIb efficacy study.
Main Methods:
- * Phase I, double-blind, randomized controlled trial.
- * 60 children aged 1-4 randomized to RTS,S/AS02A or Engerix-B.
- * Safety and reactogenicity monitored via clinical/laboratory analyses and adverse event assessment.
Main Results:
- * RTS,S/AS02A was safe and well-tolerated, with no vaccine-related serious adverse events.
- * Adverse event rates were comparable to previous studies; Grade 3 events were infrequent, transient, and resolved without sequelae.
- * The vaccine was highly immunogenic, inducing strong antibody responses against circumsporozoite protein and hepatitis B surface antigen.
Conclusions:
- * The pediatric dose of RTS,S/AS02A is safe and immunogenic in Mozambican children.
- * Findings support proceeding with larger efficacy trials for this malaria vaccine candidate.
Background:
The development of a malaria vaccine remains a public health priority for sub-Saharan Africa. RTS,S/AS02A candidate malaria vaccine has been shown to be safe and immunogenic in previous studies in adults and staggered dose-escalation studies in children in The Gambia. However, genetic features and the intensity of malaria transmission may modify the safety and immune response of a vaccine.
Objective:
We carried out a phase I, double-blind randomized controlled trial in 60 children aged 1-4 in Mozambique to evaluate the safety, reactogenicity and immunogenicity of the paediatric vaccine dose (fixed 25 microg RTS,S in 0.25 ml) of RTS,S/AS02A, prior to undertaking a planned larger phase IIb proof-of-concept of efficacy study in the same population.
Method:
Children were randomized to receive either RTS,S/AS02A or Engerix-B vaccine. Monitoring of safety and reactogenicity included detailed clinical and laboratory analyses and assessment of adverse events (AEs).
Results:
The RTS,S/AS02A was found to be safe and well tolerated. Serious adverse events were balanced between both groups and none was related to vaccination. The frequency of adverse events reported with RTS, S/AS02A was comparable to previous studies in children. Grade 3 AEs were infrequent (one case of pain, one of fever in each group and some swelling greater than 20 mm in diameter), transient and resolved without sequelae. RTS,S/AS02A was highly immunogenic for anti-circumsporozoite protein antibody response and induced a strong anti-hepatitis-B surface antigen response.
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