Fig. 2.

Meta-analysis study rationalizes the application of probiotics as a preventive and treatment strategy in COVID-19. Forest plot showing pooled mean difference and 95% confidence intervals for the effect of probiotics-based therapy versus placebo controls (after adjustment for heterogeneity) on the patients with upper respiratory tract infection (URTI) (a). Funnel plot of the standard error plotted against the effect size to examine publication bias shows the effect of probiotics on upper respiratory tract infection (URTI) in different clinical trials (b). The perpendicular line to the x-axis represents the pooled effect size. The studies outside the triangle represent positive or negative bias. The lack of significant asymmetry in the funnel plot suggests the absence of publication bias