Systematic review of clinical trials on the potential of probiotics for the treatment of Covid-19

In recent decades, new deadly coronaviruses causing highly infectious diseases have emerged in human society, resulting in threats to public health and the global economy. In December 2019, in the province of Wuhan, China, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged. This infection was classified as the coronavirus disease 2019 (COVID-19) pandemic. Probiotics are live microorganisms whose administration in adequate quantities has been associated with health benefits for the host, contributing to the treatment and prevention of multiple pathologies. The present study aims to review scientific evidence on the impact of probiotic treatment on the progression of morbidity due to SARS-CoV-2. The research was conducted in the Cochrane Library, Clinical Trials, EBSCO, Medline, Web of Science, and Science Direct databases. Inclusion criteria were as follows: study period between 2019 and 2023; language in English or Portuguese; methodology based on clinical trials; studies in humans with a confirmed diagnosis of SARS-CoV-2 and administration of probiotics in the treatment of the pathology. Five studies were included in this review, recruiting a total of patients ranging from 23 and 300 individuals. The main positive results of the probiotic intervention compared to the control group were nearly an improvement in digestive symptoms (65% vs 88%, p-value 0.06) and overall symptoms (88.6% vs 70.8%; p-value 0.03). Also, in the probiotic group, there was an increase in serum concentrations of Immunoglobulin G (IgG) in the receptor-binding domain/spike 1 (RBD/S1) (225.9 vs 105.6 binding antibody units/mL, p-value < 0.05). The major limitation is related to the fact that, in all five studies, patients were concomitantly treated with several other drugs whose action may have influenced the observed results. The conducted studies suggest that the use of probiotics enhances a decrease in morbidity in SARS-CoV-2, although more studies are needed to confirm their efficacy in the disease.