"Some researchers are taking a more holistic approach to vaccine adjuvants. Probiotics—beneficial, not pathogenic, microbes—have become famous recently for their ability to help influence the immune system. Though many studies focus on probiotics’ ability to stave off an overactive immune response, it turns out they can also boost the immune system.
'Probiotics have a whole range of different effects,' including enhancing immune responses, noted Paul Licciardi, an immunologist and vaccinologist at Murdoch Children’s Research Institute in Australia. A 2011 trial of live attenuated influenza vaccine, for example, showed that more patients given a 28-day course of the patented probiotic Lactobacillus rhamnosus GG produced protective antibodies to seasonal flu than patients given the vaccine alone."
Bacteria Boost Vaccine Effectiveness | The Scientist Magazine®