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Childhood Humoral Immunity During and After COVID-19 Lockdowns

Coralie Mallebranche1, Emeline Vinatier2, Julien Lejeune3

  • 1From the University of Angers, Université de Nantes, Inserm, CNRS, CRCI2NA, SFR ICAT, CHU Angers, Pediatric Immuno-hemato-oncology Unit, Angers, France.

The Pediatric Infectious Disease Journal
|May 29, 2025
PubMed

Insights

COVID-19 lockdowns caused a temporary drop in immunoglobulin G (IgG) levels, especially in children. Antibody levels returned to normal after restrictions were lifted, suggesting a brief immune gap.

Area of Science:

  • Immunology
  • Epidemiology
  • Public Health

Background:

  • The COVID-19 pandemic necessitated widespread public health interventions, including lockdowns.
  • Understanding the impact of these non-pharmaceutical interventions on immune system function is crucial.

Purpose of the Study:

  • To investigate the effect of COVID-19 lockdown periods on immunoglobulin G (IgG) levels in a diverse patient population.
  • To assess the duration of any observed changes in IgG levels.

Main Methods:

  • Serum samples were collected from 3678 hospital inpatients and outpatients.
  • Samples were obtained before, during, and after COVID-19 lockdown periods.
  • Immunoglobulin G levels were quantified and analyzed across different time points and age groups.

Main Results:

  • A significant decrease in overall IgG levels was observed during the lockdown periods.
  • Children aged 3-10 years showed a particularly pronounced reduction in IgG levels.
  • Following the lifting of restrictions, immunoglobulin levels normalized within a few months.

Conclusions:

  • COVID-19 lockdowns may have induced a transient humoral immune gap.
  • The immune system demonstrated resilience, with antibody levels recovering post-restriction.
  • Further research is warranted to explore the long-term implications, if any, of such immune fluctuations.

Keywords:
Immunoglobulin GImmunologic MemorySARS-CoV-2non-pharmaceutical interventions

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