Effect of Lactobacillus paracasei subsp. paracasei, L. casei 431 on immune response to influenza vaccination and upper respiratory tract infections in healthy adult volunteers: a randomized, double-blind, placebo-controlled, parallel-group study.

Background: Probiotics can modulate the immune system in healthy individuals and may help reduce symptoms related to respiratory infections.

Objective: The objective of the study was to investigate the effect of the probiotic strain Lactobacillus paracasei subsp. paracasei, L.