Assessing Vaccine Effectiveness of R21/Matrix-M Across Malaria Transmission Settings (AVERT)

The AVERT study is a prospective observational test-negative case control study evaluating the real-world effectiveness of the R21/Matrix-M malaria vaccine among children younger than 5 years in Burkina Faso and Uganda. Children who seek outpatient care with suspected malaria and are eligible for the national R21/Matrix-M vaccination program will be enrolled. Malaria infection will be determined by blood smear microscopy. Children with a positive microscopy result will be classified as cases and children with a negative result as controls. Vaccination history, including the number and timing of doses, will be obtained primarily from vaccination cards or other written records. Vaccine effectiveness will be estimated by comparing the odds of vaccination among cases and controls.

Inclusion Criteria: * Residence in an area where R21/Matrix-M is implemented and within the catchment area of a selected study facility. * Younger than 5 years and eligibleto receive R21/Matrix-M under the national vaccination schedule at rollout. * Meets the country definition of suspected malaria, generally axillary temperature of at least 37.5 degrees Celsius or a history of fever within the previous 24 hours, and is undergoing malaria testing. * Written informed consent provided by an adult caregiver aged 18 years or older. Exclusion Criteria: * Caregiver is unable or unwilling to provide informed consent. * Severe non-malaria illness at presentation that would interfere with study participation. * Repeat presentation within the protocol-defined exclusion window after a previous enrollment: within 14 days after a microscopy-positive visit; or more than 7 but fewer than 14 days after a microscopy-negative visit. A microscopy-negative visit followed by a positive diagnosis within 7 days will be reclassified as positive rather than treated as a new enrollment. * Documented receipt of any RTS,S malaria vaccine dose.