The flu season has been brutal so far, with many reported cases involving severe illnesses.

Since the start of the influenza season, 578 people have been hospitalized with laboratory-confirmed influenza, according to the Minnesota Department of Public Health reports for the 2012-2013 season. This is up from 30 people who were reportedly hospitalized this flu season in a report from last month. 

In addition, four influenza-related deaths have been confirmed this season, including St. Louis Park High School student Carly Christenson.

Christenson, 14, came home from basketball practice with a bad sore throat Dec. 20 and was admitted to Children's Hospital in Minneapolis on Dec. 24. On Jan. 3, doctors gave her a 50-50 chance to survive.

This time last year, flu cases were lower in Minnesota than they are now, according to data on Google's Flu Trends. (Minnetonka-specific data is not available on Flu Trends, but flu cases in the Twin Cities metro are in line with the state as a whole.)

Overall in Minnesota, activity is categorized as "high," while it was categorized as "low" at this time in 2011, according to Flu Trends.

The Centers for Disease Control and Prevention offers the following information:

• Who should get vaccinated
• When to get vaccinated
• Selecting a flu vaccine
• Symptoms, complications and severity
• Treatment if you get the flu
• How flu spreads