The current study is a follow-up to 2 previous parent studies, a dose-selection study with 3 different dose-levels of the altSonflex1-2-3 vaccine in a schedule of 3 vaccinations (H06\_01TP study \[NCT05073003, 212149\]) and a study with an alternate 2 vaccination schedule H06\_02TP study \[NCT06663436, 219449\]). The current study aims to assess the longevity of the immune response to the selected dose of the altSonflex1-2-3 vaccine 1, 2, and 3 years after the last vaccination in African children. The study involves no new vaccinations but will collect immunogenicity blood samples from participants.