With the beginning of fall comes the beginning of the flu season, which usually peaks in the U.S. between December and February. While getting the flu is a miserable experience for most, it also can be quite dangerous. The World Health Organization estimates that flu epidemics cause three to five million cases of severe illness and between 250,000 and 500,000 deaths annually worldwide. Preventing the spread of the flu can save both misery and lives. One of the main ways to prevent catching the flu is through vaccination.
However, vaccination is not guaranteed to prevent someone from catching the flu for a number of reasons. Sometimes, it’s because creating the annual vaccine requires some guesswork, and the most prevalent flu strains aren’t included. Sometimes, manufacturing problems can lead to less effective vaccines, as was the case for the 2016-2017 flu season. And sometimes, it’s because the immune response isn’t as strong as it could be, so the vaccine doesn’t stick. This particular issue may be more prevalent in elderly people. Sometimes, adjuvants are included with a flu shot in order to boost the immune response, but there are safety concerns about these.
One possibly safer way to boost the immune response to the flu shot is by supplementing with probiotics or prebiotics. There’s evidence to suggest that both can positively influence the immune response. It also seems that the way both prebiotics and probiotics influence the immune system could improve the immune response to vaccination. This implies that supplementation could help make flu shots stick. This hypothesis has been examined in multiple clinical trials. However, some of these trials have come up positive, while others have found no evidence of an effect. In order to make sense of the evidence to date, the study under consideration set out to conduct a systematic review and meta-analysis of the effects of pre- and probiotic supplementation on flu vaccination efficacy.
The flu vaccine, while very useful, doesn’t always stick. Probiotics and prebiotics are thought to positively influence immune function, opening up the possibility that supplementing with them around the time of getting the flu vaccine could make the vaccine more effective.