Host transcriptional response to SARS-CoV-2 infection in COVID-19 patients

BackgroundOne of the most perplexing aspects of infection with the SARS-CoV-2 virus has been the variable response elicited in its human hosts. Investigating the transcriptional changes in individuals affected by COVID-19 can help understand and predict the degree of illness and guide clinical outcomes in diverse backgrounds. MethodsAnalysis of host transcriptome variations via RNA sequencing from naso/oropharyngeal swabs of COVID-19 patients. ResultsWe report strong upregulation of the innate immune response, especially type I interferon pathway, upon SARS-CoV-2 infection. Upregulated genes were subjected to a comparative meta-analysis using global datasets to identify a common network of interferon stimulated and viral response genes that mediate the host response and resolution of infection. A large proportion of mis-regulated genes showed a reduction in expression level, suggesting an overall decrease in host mRNA production. Significantly downregulated genes included those encoding olfactory, taste and neuro-sensory receptors. Many pro-inflammatory markers and cytokines were also downregulated or remained unchanged in the COVID-19 patients. Finally, a large number of non-coding RNAs were identified as down-regulated, with a few of the lncRNAs associated with functional roles in directing the response to viral infection. ConclusionsSARS-CoV-2 infection results in the robust activation of the bodys innate immunity. Reduction of gene expression is well correlated with the clinical manifestations and symptoms of COVID-19 such as the loss of smell and taste, and myocardial and neurological complications. This study provides a critical dataset of genes that will enhance our understanding of the nature and prognosis of COVID-19.

Detection of SARS-CoV-2 in the air from hospitals and closed rooms occupied by COVID-19 patients

To understand air transmission characteristics of SARS-CoV-2 and risks for health care personnel and visitors to hospitals, we analyzed air samples collected from various enclosures in hospitals at Hyderabad and Mohali and performed closed room experiments with COVID-19 positive individuals. We collected 64 air samples from COVID and non-COVID areas of various hospitals and 17 samples from closed rooms occupied by COVID patients. 4 samples from COVID care areas were positive for SARS-CoV-2 with no obvious predilection towards ICU/non-ICU areas in the hospital samples. In the closed room experiments, where one or more COVID-19 patients spent a short duration of time, one sample - collected immediately after the departure of three symptomatic patients from the room - was positive. Our results indicate that the chance of picking up SARS-CoV-2 in the air is directly related to a number of COVID positive cases in the room, their symptomatic status, and the duration of exposure and that the demarcation of hospital areas into COVID and non-COVID areas is a successful strategy to prevent cross infections. In neutral environmental conditions, the virus does not seem to spread farther away from the patients, especially if they are asymptomatic, giving an objective evidence for the effectiveness of physical distancing in curbing the spread of the epidemic.