The seasonal flu shot may carry additional benefits for your heart.  Getting that seasonal flu vaccine may cut your risk of heart attack by 20 percent. That’s according to a new UK study of adults.  Good news says Dr. Jeffrey Kahn, Director of Immunology at UT Southwestern in Dallas.  He says people who received vaccinations early in the season showed the greatest benefit. Kahn says they’re not clear why the heart is protected, but  influenza  infection is known to put additional strain on the heart.  All three strains of the flu are already showing up here in north Texas.