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First Author:  Hye Kyung Lee 

Journal/preprint namemedRxiv preprint  

DOI: 10.1101/2020.09.01.20185884  

Tags:  asymptomatic COVID19 


The authors investigate immune cell transcriptomes from 43 asymptomatic seropositive and 52 highly exposed seronegative individuals to investigate immune responses in asymptomatic COVID-19. They also compare four mildly symptomatic seropositive cases to four highly exposed seronegative participants from the same family to validate their approach. The authors do not detect any differences in chemokine and cytokine expression between seronegative and asymptomatic seropositive cases and only little change in PBMC gene expression. 

Research Highlights 

  1. 16 hallmark gene sets are expressed at higher levels in mild cases compared to seronegative ones. 5 of them are involved in immune regulation, while 11 are not directly linked to the immune response. 

  1. Very little change (11 induced, 7 down-regulated) is detected in PBMC gene expression between seropositive asymptomatic and seronegative participants (data stated to be in supplements which cannot be accessed) 

  1. No differences are observed in chemokine and cytokine levels of seropositive asymptomatic and seronegative patients. 

Impact for COVID-19 research:  

Very little clinical impact. It’s interesting to see that asymptomatic COVID-19 does not seem to trigger an immune response. Would be interesting to investigate gene expression differences in non-immune cells.  

It would be good to see the gene expression data for asymptomatic and seronegative participants and to compare affected genes to mild and severe cases of COVID-19. 


  • In silico 

  • Key Techniques: RNA sequencing from PBMCs, cytokine profiling from plasma 


  • The patient sample is very specific, all participants are from a small rural region in Austria with very low predefined risk factors for COVID-19. 

  • Supplementary figures are not accessible, would be especially interesting to see data on PBMC gene expression for seronegative and seropositive asymptomatic participants.