CDC estimates that, from October 1, 2018, through May 4, 2019, there have been 531,000 – 647,000 flu hospitalizations, and more than 27 million were affected by flu-related illnesses, according to the CDC. In addition to symptoms including sore throat, aches and fever, the flu can lead to serious health complications such as pneumonia.  One of the most important steps you can take to avoid serious, flu-related illnesses is to be vaccinated.