Serum ferritin as a predictive biomarker in COVID-19. A systematic review, meta-analysis and meta-regression analysis.

Ferritin is a known inflammatory biomarker in COVID-19. However, many factors and co-morbidities can confound the level of serum ferritin. This current metaanalysis evaluates serum ferritin level in different severity levels in COVID-19. Studies evaluating serum ferritin level in different clinical contexts (COVID-19 vs. control, mild to moderate vs. severe to critical, non-survivor vs. survivor, organ involvement, ICU and mechanical ventilation requirement) were included (total 9 literature databases searched). Metaanalysis and metaregression was carried out using metaphor "R" package. Compared to control (COVID-19 negative), higher ferritin levels were found among the COVID-19 patients [SMD -0.889 (95% C.I. -1.201, -0.577), I2 = 85%]. Severe to critical COVID-19 patients showed higher ferritin levels compared to mild to moderate COVID-19 patients [SMD 0.882 (0.738, 1.026), I2 = 85%]. In meta-regression, high heterogeneity was observed could be attributed to difference in "mean age", and "percentage of population with concomitant co-morbidities". Non-survivors had higher serum ferritin level compared to survivors [SMD 0.992 (0.672, 1.172), I2 = 92.33%]. In meta-regression, high heterogeneity observed could be attributed to difference in "mean age" and "percentage of male sex". Patients requiring ICU [SMD 0.674 (0.515 to 0.833), I2 = 80%] and mechanical ventilation [SMD 0.430 (0.258, 0.602), I2 = 32%] had higher serum ferritin levels compared to those who didn't. To conclude, serum ferritin level may serve as an important biomarker which can aid in COVID-19 management. However, presence of other co-morbid conditions/confounders warrants cautious interpretation.

COVID-19 and Gut Microbiota: A Potential Connection.

Currently, world is facing a global outbreak causing a pandemic threat known as COVID-19. This infectious disease is triggered by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Gut microbiota harbours multi species community with a strong impact on host immune homeostasis. However, our knowledge about this gut microbiota and its symbiotic relationship with immune activation in association with SARS-CoV-2 is limited. Unbalanced bacterial flora with too many opportunistic infections can shift immune system towards a cascade of inflammatory responses leading to multi organ damage. This review will highlight immune-regulation via various mechanisms in SARS-CoV-2 infection. Diet has an unbelievable influence on gut microbiome that allows a new state of homeostasis to be reached through timing, frequency and duration of intake. This review article focuses on gut, lung microbiota and immunomodulation with specific attention on immune activation by gut microbiota.