The Effect of Probiotics on Respiratory Tract Infection with Special Emphasis on COVID-19: A Periodic Review during 2010-2020.

To evaluate the effects of probiotic on patient's respiratory tract infection (RTI), a systematic review was conducted on randomized controlled trials (RCTs). PubMed, Google Scholar, Embase, Scopus, Clinicaltrials.gov, and International Clinical Trials Registry Platform (ICTRP) databases were systematically searched for the following keywords from January 2010 to January 2020: including respiratory tract infection, probiotics, viral infection, COVID-19, and clinical trial. A total of 27 clinical trials conducted on 9,433 patients with RTI and 10 ongoing clinical studies of probiotics intervention in COVID-19 were reviewed. In this systematic review, were attempted to study the potency of probiotics for the hindrance and/or treatment of RTI diseases extensively, which may be practical to conflict the new coronavirus (COVID-19). Overall, probiotics could significantly increase the plasma levels of cytokines, the effect of influenzae vaccine, and quality of life as well as reducing the titre of viruses and the incidence and duration of respiratory infections. These antiviral and immune-modulating activities and their ability to stimulate interferon production recommended that to use probiotics as adjunctive therapy to prevent COVID-19. The rapid spread of the virus has affected the entire world socially and economically. Given this extensive research on RCTs, were expected probiotics to be a rational complementary treatment for RTI disease and a viable option for faster recovery.