(HealthDay News) -- When the mastoid bone in the skull becomes infected, it's called mastoiditis. Often it's triggered by an infection in the middle ear, and it's most common in children.
The U.S. National Library of Medicine mentions these symptoms that may indicate mastoiditis:
The Flu Vaccine Can Lower Your Risk Of Heart Attack And Stroke — Even If You Wind Up Infected
Childhood Flu Shots Prevent Millions of Cases, Study Finds
New Flu Variant Could Bring Another Severe U.S. Season
Flu Season Starts Early in NYC as Cases Rise Fast
They Spent Hours In A Room Full Of Flu Patients And Walked Out Healthy — Here's How