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

doi:10.1093/ofid/ofad608

Innate and Adaptive Cell-Mediated Immune Responses to a COVID-19 mRNA Vaccine in Young Children

Open Forum Infect Dis. 2023 Dec 2;10(12):ofad608. doi: 10.1093/ofid/ofad608. eCollection 2023 Dec.

Authors

Adriana Weinberg^{1

2

3}, Michael J Johnson¹, Krystle Garth¹, Elena W Y Hsieh^{1

4}, Ross Kedl⁴, Daniela Weiskopf^{5

6}, Mattie Cassaday⁴, Cody Rester⁴, Berenice Cabrera-Martinez⁴, Ryan M Baxter⁴, Myron J Levin^{1

2}

Affiliations

¹ Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
² Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
³ Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
⁴ Department of Microbiology and Immunology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
⁵ Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology, La Jolla, California, USA.
⁶ Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California, San Diego, La Jolla, California, USA.

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 aged 6 to 60 months.

Methods: Blood obtained from participants in a randomized placebo-controlled trial of an mRNA vaccine before and 1 month after the first dose was used for antibody measurements and CMI (flow cytometry).

Results: We enrolled 29 children with a mean age of 28.5 months (SD, 15.7). Antibody studies revealed that 10 participants were infected with SARS-CoV-2 prevaccination. Ex vivo stimulation of peripheral blood mononuclear cells with SARS-CoV-2 spike peptides showed significant increases pre- to postimmunization of activated conventional CD4+ and γδ T cells, natural killer cells, monocytes, and conventional dendritic cells but not mucosa-associated innate T cells. Conventional T-cell, monocyte, and conventional dendritic cell responses in children were higher immediately after vaccination than after SARS-CoV-2 infection. The fold increase in CMI pre- to postvaccination did not differ between children previously infected with SARS-CoV-2 and those uninfected.

Conclusions: Children aged 6 to 60 months who were vaccinated with a COVID-19 mRNA vaccine developed robust CMI responses, including adaptive and innate immunity.

Keywords: COVID-19 mRNA vaccines; SARS-CoV-2 infection; cell-mediated immunity; children; trained immunity.

Abstract

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