Probiotics Against Viruses; COVID-19 is a Paper Tiger: A Systematic Review

Endocr Metab Immune Disord Drug Targets. 2021;21(7):1252-1260. doi: 10.2174/1871530320666200917114033.


Background: Probiotics can improve immune function leading to the prevention and management of viral infections like SARS-CoV-2 infection (COVID-19 disease).

Methods: We searched PubMed, EMBASE, Google Scholar, Science Direct, Scopus, and Web of Science up to May 2020 to identify interventional & observational studies documenting the effects of probiotics on incidence, severity, duration, and other clinical manifestations of viral infections, especially SARS-CoV-2-induced.

Results: From a total of 91 records, 24 studies were obtained and classified into three domains based on the efficacy of probiotics on 1) shortening the period and severity of infections (n=9), 2) incidence (n=6), and 3) other clinical complications that may be followed by viral disorders (n=9). Identified probiotics have positive effects on the mentioned domains.

Conclusion: Based on the evidence, some probiotic strains may be useful in SARS-CoV-2 infection; randomized trials are needed to show the facts.

Keywords: COVID-19; SARS-CoV-2; Viral diseases; immunity.; microbiome; probiotics.

Publication types

  • Case Reports
  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Animals
  • Antiviral Agents / administration & dosage
  • COVID-19 / diagnosis
  • COVID-19 / diet therapy*
  • COVID-19 / immunology*
  • Humans
  • Observational Studies as Topic / methods
  • Probiotics / administration & dosage*
  • SARS-CoV-2 / immunology*


  • Antiviral Agents