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Neonatal and Children's Immune System and COVID-19: Biased Immune Tolerance versus Resistance Strategy
Shokrollah Elahi1,2,3,4
1School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G2E1, Canada; elahi@ualberta.ca.
Insights
Children and infants often show mild or no COVID-19 symptoms due to unique immune system traits. Their immune tolerance and recent vaccinations may offer protection against severe coronavirus disease.
Area of Science:
- Immunology
- Pediatrics
- Infectious Diseases
Background:
- COVID-19 presents as a significant global health issue.
- Infants, children, and adolescents typically experience mild or asymptomatic infections.
- Other coronavirus infections (SARS, MERS) also show milder pediatric presentations.
Purpose of the Study:
- To investigate the immunological reasons behind the milder COVID-19 presentation in pediatric populations.
- To explore the differences in immune system responses between children and adults regarding viral infections.
Main Methods:
- Review of recent evidence on pediatric COVID-19 and other coronavirus infections.
- Analysis of fundamental differences in neonatal and adult immune systems.
- Consideration of vaccination history and its impact on immune responses in younger individuals.
Main Results:
- Neonatal immune systems exhibit biased immune tolerance rather than resistance to microorganisms.
- Frequent or recent vaccinations in children may induce trained immunity.
- Physiological factors like immunosuppressive cells and regulated immune systems contribute to limited reactions.
Conclusions:
- The distinct immune characteristics of children, including immune tolerance and trained immunity, likely contribute to their reduced susceptibility to severe COVID-19.
- Understanding these differences can inform strategies for managing infectious diseases in pediatric populations.
Abstract:
The recent outbreak of COVID-19 has emerged as a major global health concern. Although susceptible to infection, recent evidence indicates mostly asymptomatic or mild presentation of the disease in infants, children, and adolescents. Similar observations were made for acute respiratory infections caused by other coronaviruses (severe acute respiratory syndrome and Middle East respiratory syndrome). These observations suggest that the immune system behaves differently in children than adults. Recent developments in the field demonstrated fundamental differences in the neonatal immune system as compared with adults, whereby infants respond to microorganisms through biased immune tolerance rather than resistance strategies. Similarly, more frequent/recent vaccinations in children and younger populations may result in trained immunity. Therefore, the physiological abundance of certain immunosuppressive cells, a tightly regulated immune system, and/or exposure to attenuated vaccines may enhance trained immunity to limit excessive immune reaction to COVID-19 in the young.
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