The flu vaccine is formulated each year to match the predicted strains expected to cause most human suffering that year. Influenza has a segmented RNA genome th

The flu vaccine is formulated each year to match the predicted strains expected to cause most human suffering that year. Influenza has a segmented RNA genome that makes it more likely to mutate and change its antigen expression. The flu vaccine saves a significant number of lives each year. https://en.wikipedia.org/wiki/Influenza#Replication https://en.wikipedia.org/wiki/Influenza#Replication https://www.cdc.gov/flu/news/flu-vaccine-saved-lives.htm https://www.cdc.gov/flu/news/flu-vaccine-saved-lives.htm The shingles vaccine bolsters immunity towards the chicken pox virus so that even when depressed your immune system has enough T-cells against the virus that it does not reactivate. Shingrex is 97% effective at preventing shingles. https://www.ncbi.nlm.nih.gov/pubmed/25916341 https://www.ncbi.nlm.nih.gov/pubmed/25916341