Participants in multiple placebo-controlled trials experienced delayed onset of COVID-19 and fewer symptoms, including post-COVID syndrome.102–104 However, Jesperson et al. found L. paracasei only had positive symptomatic effects.105 LGG has also had positive results in influenza vaccinees, with increased IgA and IgG titers following the use of LGG, L. plantarum and Lactobacillus fermentum. Here, CD79A is linked to influenza.