The flu vaccine isnt perfect, but youre still better off getting it than not. In a good year, the flu vaccine is about 70 percent effective; if were unlucky, the rate can dip lower.
Two years ago, the shot was only 23 percent effective. Last years did better, around 60 percent. The exact rate depends on which strains of flu are circulating in your area, but most years the effectiveness hovers around 50 percent.
Think of it this way: if somebody coughs on you during flu season, wouldnt you like to have a coin-flip chance of escaping unharmed? Fifty percent is a lot better than zero. The Centers for Disease Control and Prevention (CDC) summarizes: Influenza vaccination, even when effectiveness is reduced, can prevent thousands of hospitalizations.
Why are flu shots often ineffective? Other vaccines have better track records: the measles vaccine is 97 percent effective, for example, in children who get both of the recommended doses. Here are a few reasons that make flu vaccine a weird one.
There isnt just one flu. Flu viruses mutate a lot, so we need a new shot every year. The people who make flu shots have to choose in the spring which strains should go in the shot for that fall and winter, and if they guess wrong, the shot will be less effective. (Thats what happened in 2014, the 23 percent effectiveness year.)
Some people dont respond well to the vaccine. Flu shots are less effective in children under age 2, and adults over 65. Other factors and health conditions can affect how well youll respond.
