Innate and Adaptive Cell-Mediated Immune Responses to a COVID-19 mRNA Vaccine in Young Children
Adriana Weinberg, Michael J Johnson, Krystle Garth, Elena W Y Hsieh, Ross Kedl, Daniela Weiskopf, Mattie Cassaday, Cody Rester, Berenice Cabrera-Martinez, Ryan M Baxter, Myron J Levin- Infectious Diseases
- Oncology
Abstract
Background
There is little information on cell-mediated immunity (CMI) to COVID-19 mRNA vaccines in children. We studied adaptive and innate CMI in vaccinated children 6 to 60 months of age.
Methods
Blood obtained from participants in a randomized, placebo-controlled trial of an mRNA vaccine before and one month after the first dose was used for antibody measurements and CMI (flow cytometry).
Results
We enrolled 29 children with mean (s.d.) age of 28.5 (15.7) months. Antibody studies revealed that 10 participants were infected with SARS-CoV-2 pre-vaccination. Ex-vivo stimulation of peripheral blood mononuclear cells with SARS-CoV-2 Spike peptides showed significant increases from pre- to post-immunization of activated conventional CD4 + and γδ T cells, NK, monocytes, and conventional dendritic cells (cDC) but not mucosa-associated innate T cells (MAIT). Conventional T cell, monocyte, and cDC responses in children were higher immediately after vaccination than after SARS-CoV-2 infection. The fold-increase in CMI from pre- to post-vaccination did not differ between previously SARS-CoV-2-infected and uninfected children.
Conclusions
Children (6-60 months of age) vaccinated with a COVID-19 mRNA vaccine developed robust CMI responses, including adaptive and innate immunity.