Frontiers in Immunology (Oct 2021)

Children and Adults in a Household Cohort Study Have Robust Longitudinal Immune Responses Following SARS-CoV-2 Infection or Exposure

  • Melanie R. Neeland,
  • Melanie R. Neeland,
  • Samantha Bannister,
  • Samantha Bannister,
  • Samantha Bannister,
  • Vanessa Clifford,
  • Vanessa Clifford,
  • Vanessa Clifford,
  • Vanessa Clifford,
  • Jill Nguyen,
  • Kate Dohle,
  • Isabella Overmars,
  • Zheng Quan Toh,
  • Zheng Quan Toh,
  • Jeremy Anderson,
  • Jeremy Anderson,
  • Celeste M. Donato,
  • Celeste M. Donato,
  • Sohinee Sarkar,
  • Sohinee Sarkar,
  • Lien Anh Ha Do,
  • Lien Anh Ha Do,
  • Conor McCafferty,
  • Paul V. Licciardi,
  • Paul V. Licciardi,
  • Vera Ignjatovic,
  • Vera Ignjatovic,
  • Paul Monagle,
  • Paul Monagle,
  • Paul Monagle,
  • Paul Monagle,
  • Julie E. Bines,
  • Julie E. Bines,
  • Julie E. Bines,
  • Kim Mulholland,
  • Kim Mulholland,
  • Kim Mulholland,
  • Nigel Curtis,
  • Nigel Curtis,
  • Nigel Curtis,
  • Sarah McNab,
  • Sarah McNab,
  • Sarah McNab,
  • Andrew C. Steer,
  • Andrew C. Steer,
  • Andrew C. Steer,
  • David P. Burgner,
  • David P. Burgner,
  • David P. Burgner,
  • Richard Saffery,
  • Richard Saffery,
  • Shidan Tosif,
  • Shidan Tosif,
  • Shidan Tosif,
  • Nigel W. Crawford,
  • Nigel W. Crawford,
  • Nigel W. Crawford

DOI
https://doi.org/10.3389/fimmu.2021.741639
Journal volume & issue
Vol. 12

Abstract

Read online

Children have reduced severity of COVID-19 compared to adults and typically have mild or asymptomatic disease. The immunological mechanisms underlying these age-related differences in clinical outcomes remain unexplained. Here, we quantify 23 immune cell populations in 141 samples from children and adults with mild COVID-19 and their PCR-negative close household contacts at acute and convalescent time points. Children with COVID-19 displayed marked reductions in myeloid cells during infection, most prominent in children under the age of five. Recovery from infection in both children and adults was characterised by the generation of CD8 TCM and CD4 TCM up to 9 weeks post infection. SARS-CoV-2-exposed close contacts also had immunological changes over time despite no evidence of confirmed SARS-CoV-2 infection on PCR testing. This included an increase in low-density neutrophils during convalescence in both exposed children and adults, as well as increases in CD8 TCM and CD4 TCM in exposed adults. In comparison to children with other common respiratory viral infections, those with COVID-19 had a greater change in innate and T cell-mediated immune responses over time. These findings provide new mechanistic insights into the immune response during and after recovery from COVID-19 in both children and adults.

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