Statistically significant lower risk is seen for mortality, hospitalization, progression, recovery, and cases. 13 studies from 12 independent teams in 9 countries show statistically significant improvements.
Meta analysis using the most serious outcome reported shows 28% [18‑37%] lower risk. Results are similar for Randomized Controlled Trials, higher quality studies, and peer-reviewed studies. Better results are seen with early treatment.
Results are robust — in exclusion sensitivity analysis 24 of 26 studies must be excluded to avoid finding statistically significant efficacy in pooled analysis.
The immune effects of probiotics are strain-specific and studies use different strains.
No treatment or intervention is 100% effective. All practical, effective, and safe means should be used based on risk/benefit analysis. Multiple treatments are typically used in combination, and other treatments are more effective. The quality of non-prescription supplements can vary widely Crawford, Crighton. Many probiotic supplements may not include labeled ingredients Hazan.
All data to reproduce this paper and sources are in the appendix. Other meta analyses show significant improvements with probiotics for hospitalization Tian and recovery Neris Almeida Viana, Tian.
Covid Analysis et al., Apr 2024, preprint, 1 author.
