Yearly immunization with the inactivated influenza vaccine(What is a PDF document?) (flu shot) or the nasal spray flu vaccine(What is a PDF document?) prevents flu infection and its complications in most people.

Yearly immunization with the inactivated influenza vaccine(What is a PDF document?) (flu shot) or the nasal spray flu vaccine(What is a PDF document?) prevents flu infection and its complications in most people.

Have heart disease.

Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites.

Some infectious diseases can be passed from person to person. Some are transmitted by bites from insects or animals.

Signs and symptoms vary depending on the organism causing the infection, but often include fever and fatigue.