Researchers are exploring whether these ubiquitous fluorinated molecules might worsen infections or hamper vaccine effectiveness.
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Edited by Robert L. Coffman, University of California, Santa Cruz, Portola Valley, CA, and approved August 14, 2020 (received for review July 8, 2020)
Abstract
The reduced development of COVID-19 for children compared to adults provides some tantalizing clues on the pathogenesis and transmissibility of this pandemic virus. First, ACE2, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor, is reduced in the respiratory tract in children. Second, coronavirus associated with common colds in children may offer some protection, due to cross-reactive humoral immunity and T cell immunity between common coronaviruses and SARS-CoV-2. Third, T helper 2 immune responses are protective in children. Fourth, surprisingly, eosinophilia, associated with T helper 2, may be protective. Fifth, children generally produce lower levels of inflammatory cytokines. Finally, the influence of the downturn in the global economy, the impact of living in quarters among families who are the most at risk, and factors including the openings of some schools, are considered. Those most disadvantaged socioeconomically may suffer disproportionately with COVID-19.
Footnotes
- ↵1To whom correspondence may be addressed. Email: steinman{at}stanford.edu.
Author contributions: J.B.S., F.M.L., P.P.H., N.K., and L.S. analyzed data and wrote the paper.
Competing interest statement: N.K. has consulted with Biogen Idec, Boehringer Ingelheim, Third Rock, Pliant, Samumed, NuMedii, Indaloo, Theravance, LifeMax, Three Lake Partners, RohBar, and reports a grant from Veracyte. N.K. has patents on New Therapies in Pulmonary Fibrosis and Peripheral Blood Gene Expression Biomarkers. All these consultations are outside of this work. L.S. has consulted with Roche, Novartis, Tolerion, Atreca, TG Therapeutics, and Atara Biopharma. All these consultations are outside of the scope of this work.
This article is a PNAS Direct Submission.
Data Availability.
All study data are included in the article.
- Copyright © 2020 the Author(s). Published by PNAS.
This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).
Reduced development of COVID-19 in children reveals molecular checkpoints gating pathogenesis illuminating potential therapeutics
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- ACE2 Expression Is Lower in the Respiratory Tracts of Children
- Impact of Frequent Respiratory Infections in Childhood and Virologic and Immunologic Interference
- A Surprising Potential Protective Benefit of Th2 Immunity in Children
- Unanswered Questions and Lessons to Learn
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