Researchers at McMaster University studying mice ( as mice immune systems closely resemble human) showed that giving young mice the flu vaccine protected them against getting illnesses when they were older. The older mice that did not get the flu vaccine when they were young got diseases sooner and got much worse infections with flu.

Although no studies have yet revealed similar results in humans, there is thought that by giving yearly flu vaccines to children and young adults this may potentially protect them from diseases such as dementia and heart disease when they are older.