Contribution of SARS-CoV-2 infection preceding COVID-19 mRNA vaccination to generation of cellular and humoral immune responses in children.

Primary COVID-19 vaccination for children, 5-17 years of age, was offered in the Netherlands at a time when a substantial part of this population had already experienced a SARS-CoV-2 infection. While vaccination has been shown effective, underlying immune responses have not been extensively studied. We studied immune responsiveness to one and/or two doses of primary BNT162b2 mRNA vaccination and compared the humoral and cellular immune response in children with and without a preceding infection.

Booster Immunization Improves Memory B Cell Responses in Older Adults Unresponsive to Primary SARS-CoV-2 Immunization.

The generation of a specific long-term immune response to SARS-CoV-2 is considered important for protection against COVID-19 infection and disease. Memory B cells, responsible for the generation of antibody-producing plasmablasts upon a new antigen encounter, play an important role in this process. Therefore, the induction of memory B cell responses after primary and booster SARS-CoV-2 immunizations was investigated in the general population with an emphasis on older adults.