Why Does the Severity of COVID-19 Differ With Age?: Understanding the Mechanisms Underlying the Age Gradient in Outcome Following SARS-CoV-2 Infection.
Pediatr Infect Dis J
; 41(2): e36-e45, 2022 02 01.
Article
in English
| MEDLINE | ID: covidwho-1722659
ABSTRACT
Although there are many hypotheses for the age-related difference in the severity of COVID-19, differences in innate, adaptive and heterologous immunity, together with differences in endothelial and clotting function, are the most likely mechanisms underlying the marked age gradient. Children have a faster and stronger innate immune response to SARS-CoV-2, especially in the nasal mucosa, which rapidly controls the virus. In contrast, adults can have an overactive, dysregulated and less effective innate response that leads to uncontrolled pro-inflammatory cytokine production and tissue injury. More recent exposure to other viruses and routine vaccines in children might be associated with protective cross-reactive antibodies and T cells against SARS-CoV-2. There is less evidence to support other mechanisms that have been proposed to explain the age-related difference in outcome following SARS-CoV-2 infection, including pre-existing immunity from exposure to common circulating coronaviruses, differences in the distribution and expression of the entry receptors ACE2 and TMPRSS2, and difference in viral load.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Age Factors
/
Adaptive Immunity
/
Immunity, Heterologous
/
SARS-CoV-2
/
COVID-19
/
Immunity, Innate
Type of study:
Prognostic study
/
Randomized controlled trials
Topics:
Vaccines
Limits:
Adult
/
Child
/
Humans
Language:
English
Journal:
Pediatr Infect Dis J
Journal subject:
Communicable Diseases
/
Pediatrics
Year:
2022
Document Type:
Article
Affiliation country:
INF.0000000000003413
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