Vaccines Vaccines, 2021, This article belongs to the Special Issue Immune Ontogeny and Vaccination in Early Life, 9 (6), pp.584. ⟨10.3390/vaccines9060584⟩ Vaccines, MDPI, 2021, 9 (6), pp.584. ⟨10.3390/vaccines9060584⟩ Vaccines, Vol 9, Iss 584, p 584 (2021)