Influenza: Getting Our Attention

Influenza has become an increasingly frequent topic in the news and medical literature. Although the 1918 influenza pandemic killed more people than died during the first World War, for much of the 20th century, the disease was considered of interest primarily during the winter months, as emergency departments and hospitals filled with sick patients. Less than a decade ago, few pediatricians in the United States could differentiate influenza from other seasonal viral illnesses or could describe its impact on children. However, since the 1990s, influenza has been publicized virtually year-round. Much of this new attention concerns the threat of an influenza pandemic arising from the H5N1 avian influenza strain, which can cross-over into humans. The H5N1 strain first gained attention in Hong Kong, where influenza was then considered to be a relatively unimportant illness. The first reported outbreak of H5N1 infection in 1997 killed one-third of those with confirmed infections. Outbreaks of influenza virus H5N1 infection in humans have subsequently occurred in Vietnam, Thailand, and Cam-bodia, and outbreaks in poultry have oc-and Laos [1]. Before the H5N1 strain appeared, the impact of influenza was not well appreciated in tropical areas. In 1996, for example , Hong Kong had occurrences of influenza year-round. Fewer than 100 doses of vaccine were used annually, and the medical, social, and monetary costs of influenza were estimated to be proportional to those in developed countries [2]. After the appearance of H5N1, a study conducted in Hong Kong by Chiu et al. [3] revealed that children's hospitalization rates due to influenza in 1998 and 1999 exceeded those reported in the United States, with the risk for otherwise healthy children in Hong Kong being comparable to that for high-risk US children. These results were obtained in a study specifically designed to measure the impact of influenza with and without the confounding factor of illnesses due to respiratory syn-cytial virus and, thus, to provide a clear correlation between influenza and untoward outcomes in young children [3]. In the United States, the Centers for Disease Control and Prevention (CDC) describes influenza's impact in terms of excess mortality. The excess mortality from influenza averaged 20,000 deaths annually through the 1980s [4]; estimates from the 1990s to the present are nearly twice as high [5]. With the documented presence of H5N1 strains in various parts of the world, influenza has become of increasing concern to health care providers and policy makers. …