Efficacy of a Probiotic Consisting of Lacticaseibacillus rhamnosus PDV 1705, Bifidobacterium bifidum PDV 0903, Bifidobacterium longum subsp. infantis PDV 1911, and Bifidobacterium longum subsp. longum PDV 2301 in the Treatment of Hospitalized Patients with COVID-19: a Randomized Controlled Trial
Ivashkin et al., Probiotics Antimicrob Proteins, doi:10.1007/s12602-021-09858-5
https://c19early.org/ivashkin.html