Risk factors for poor outcomes and therapeutic strategies for seasonal and pandemic influenza.

Seasonal influenza is a leading cause of morbidity and mortality worldwide annually while pandemic influenza, a unique entity, poses distinct challenges. The pediatric population is the primary vector for epidemics and the main focus of this article. While primary prevention with universal influenza vaccination is the best protection against significant illness, the antigenic shift and drift unique to influenza viruses leave a large population at risk even with universal vaccination. Early in an epidemic various diagnostic tests are available and discussed here. However, once an epidemic is established, testing is no longer necessary for diagnosis. Groups with particular vulnerability to serious illness include those <6 mo of age, children with underlying neuromuscular disease, pulmonary disorders, or other comorbid conditions. Early treatment with neuraminidase inhibitors is recommended for those with influenza infection requiring hospitalization. Respiratory failure and need for mechanical ventilation are the leading indications for intensive care unit admission among children. Complications of influenza such as pneumonia, empyema, myocarditis and neurologic involvement increase risk for intensive care unit admission and will be discussed as will the use of extracorporeal membrane support. An overview of the epidemiology of influenza with an emphasis on risk factors for critical illness and poor patient outcomes in the pediatric population as well as treatment strategies for critically ill children will be presented. Additionally, we will address some of the unique challenges posed by pandemic influenza and mitigation strategies.