Epidemiology, clinical manifestations, and management of pandemic novel Influenza A (H1N1)

Kim, Woo Joo

Abstract

Since the first case with swine origin influenza A (H1N1) infection has been described in Mexico and the United States in April 2009, novel influenza A (H1N1) virus has been spread to all over the world. WHO has officially declared the outbreak to be an influenza pandemic by 11 June. The number of human cases and death of pandemic A (H1N1) 2009 is still increasing substantially in many countries with widespread community transmission. The natural course of novel influenza A (H1N1) still appears to be generally mild and mostly recovered. It predominantly affects children and young adults with relative sparing of older age groups, supporting a theory that older people have some cross-reactive antibodies to novel influenza A (H1N1) from previous infection or immunization. People with chronic medical conditions and pregnancy are more likely to be hospitalized with or dead from the novel influenza A (H1N1). Antiviral treatment by using neuraminidase inhibitors (oseltamivir, zanamivir) is recommended mainly for all hospitalized patients with novel influenza (H1N1) and patients who are at higher risk for seasonal influenza complications. Continued pandemic preparedness, flexible response and careful monitoring are essential because influenza viruses are unpredictable. This article reviews the current epidemiology, clinical manifestations, and management of pandemic novel influenza A (H1N1).