The severity of a flu outbreak can vary widely from one season to the next, depending on many things, including:
 • what flu viruses are spreading
 • how much flu vaccine is available
 • when the vaccine is available
 • how many people get vaccinated
 • how well the flu vaccine is matched to flu viruses that are causing illness

The flu season so far this year has been very mild, say Centers of Disease Control and Prevention (CDC) reports. In December 2014, there were a few thousand cases reported each week. In December 2015, only several hundred flu cases were confirmed per week.

Officials comment that when flu season starts later in the year, the severity is traditionally milder. But, it is still too early to tell how mild or severe the flu season will be this year.

Recent years have been pretty bad, so this flu season could end up looking good by comparison, or the number of flu cases could catch up with those of previous seasons. The classic scenario is for the first flu cases to start to appear in the U.S. in October or November. Then the pace picks up in January and peaks in February or March.

Whether this will be a mild or severe flu season remains to be seen. With the two peak months ahead, it is still too early to tell.

For more information on specific strains and vaccine recommendations, click here.