Reye's Syndrome -- a rare complication in children in which liver failure and brain swelling occur. Aspirin increases the likelihood of this syndrome and should always be avoided in children (Tylenol and ibuprofen are usually safe for children, with doctor's supervision)
The Influenza vaccine, generally available annually in October or November, provides protection against influenza strains of the coming year. Vaccines are made each year specifically for the current year. High risk individuals who should definitely get the vaccine include children 6 months of age and older in chronic care facilities; children with respiratory illnesses, such as asthma; those with metabolic diseases, including Diabetes Mellitus, kidney dysfunction; those taking immunosuppressive therapy such cancer medication; and those receiving long-term aspirin therapy.