Experimental experience suggests that microbial agents including probiotics and prebiotics (representative microbial agents) play a critical role in defending against respiratory virus infection . We aim to systematically examine these agents' effect on respiratory viral infection and encourage research into clinical applications . An electronic literature search was conducted from published data with a combination of a microbial agents search component containing synonyms for microbial agents-related terms and a customized search component for respiratory virus infection . Hazard ratio (HR), risk ratio (RR) and standard deviation (SD) were employed as effect estimates . In 45 preclinical studies, the mortality rates decreased in the respiratory viral infection models that included prebiotics or prebiotics as interventions (HR : 0.70; 95% confidence interval (CI): 0.56-0.87; P=0.002). There was a significant decrease in viral load due to improved gut microbiota (SD: -1.22; 95% CI: -1.50 to -0.94; P <0.001). Concentrations of interferon (IFN) -α (SD : 1.05; 95% CI : 0.33-1.77; P=0.004), IFN-γ (SD : 0.83; 95% CI : 0.01-1.65; P=0.05) and interleukin (IL) -12 (SD : 2.42; 95% CI : 0.32-4.52; P=0.02), IL-1β (SD : 0.01; 95% CI: -0.37 to 0.40; P=0.94) increased, whereas those of TNF-α (SD: -0.58; 95% CI: -1.59 to 0.43; P=0.26) and IL-6 (SD: -0.59; 95% CI: -1.24 to 0.07; P=0.08) decreased . Six clinical studies had lower symptom scores (SD: -0.09; 95% CI: -0.44 to 0.26; P=0.61) and less incidence of infection (RR : 0.80; 95% CI : 0.64-1.01; P=0.06). Our research indicates that probiotics and prebiotics pose a defensive possibility on respiratory viral infection and may encourage the clinical application.
Index: Antivirus, Gut microbiota, Gut-lung axis, Prebiotics, Probiotics, Viral pneumonia