Frontiers in Immunology (May 2024)

Immune responses during COVID-19 breakthrough cases in vaccinated children and adolescents

  • Daniela Rivera-Pérez,
  • Daniela Rivera-Pérez,
  • Constanza Méndez,
  • Constanza Méndez,
  • Benjamín Diethelm-Varela,
  • Benjamín Diethelm-Varela,
  • Felipe Melo-González,
  • Felipe Melo-González,
  • Felipe Melo-González,
  • Yaneisi Vázquez,
  • Yaneisi Vázquez,
  • Xing Meng,
  • Qianqian Xin,
  • Rodrigo A. Fasce,
  • Jorge Fernández,
  • Judith Mora,
  • Eugenio Ramirez,
  • Mónica L. Acevedo,
  • Mónica L. Acevedo,
  • Fernando Valiente-Echeverría,
  • Fernando Valiente-Echeverría,
  • Ricardo Soto-Rifo,
  • Ricardo Soto-Rifo,
  • Alba Grifoni,
  • Daniela Weiskopf,
  • Daniela Weiskopf,
  • Alessandro Sette,
  • Alessandro Sette,
  • Patricio Astudillo,
  • Nicole Le Corre,
  • Katia Abarca,
  • Katia Abarca,
  • Cecilia Perret,
  • Pablo A. González,
  • Pablo A. González,
  • Jorge A. Soto,
  • Jorge A. Soto,
  • Jorge A. Soto,
  • Susan M. Bueno,
  • Susan M. Bueno,
  • Alexis M. Kalergis,
  • Alexis M. Kalergis,
  • Alexis M. Kalergis

DOI
https://doi.org/10.3389/fimmu.2024.1372193
Journal volume & issue
Vol. 15

Abstract

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BackgroundVaccine effectiveness against SARS-CoV-2 infection has been somewhat limited due to the widespread dissemination of the Omicron variant, its subvariants, and the immune response dynamics of the naturally infected with the virus.MethodsTwelve subjects between 3-17 years old (yo), vaccinated with two doses of CoronaVac®, were followed and diagnosed as breakthrough cases starting 14 days after receiving the second dose. Total IgGs against different SARS-CoV-2 proteins and the neutralizing capacity of these antibodies after infection were measured in plasma. The activation of CD4+ and CD8+ T cells was evaluated in peripheral blood mononuclear cells stimulated with peptides derived from the proteins from the wild-type (WT) virus and Omicron subvariants by flow cytometry, as well as different cytokines secretion by a Multiplex assay.Results2 to 8 weeks post-infection, compared to 4 weeks after 2nd dose of vaccine, there was a 146.5-fold increase in neutralizing antibody titers against Omicron and a 38.7-fold increase against WT SARS-CoV-2. Subjects showed an increase in total IgG levels against the S1, N, M, and NSP8 proteins of the WT virus. Activated CD4+ T cells showed a significant increase in response to the BA.2 subvariant (p<0.001). Finally, the secretion of IL-2 and IFN-γ cytokines showed a discreet decrease trend after infection in some subjects.ConclusionSARS-CoV-2 infection in the pediatric population vaccinated with an inactivated SARS-CoV-2 vaccine produced an increase in neutralizing antibodies against Omicron and increased specific IgG antibodies for different SARS-CoV-2 proteins. CD4+ T cell activation was also increased, suggesting a conserved cellular response against the Omicron subvariants, whereas Th1-type cytokine secretion tended to decrease.Clinical Trial Registrationclinicaltrials.gov #NCT04992260

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