Pandemics, avian influenza A (H5N1), and a strategy for pharmacists.

Epidemics of influenza occur annually and account for more morbidity in the developed world than all other respiratory diseases combined. On average, 36,000 Americans die from influenza or its complications each year. Pandemics occur when influenza viruses undergo either antigenic drift or antigenic shift that results in a new viral strain that infects humans, when they are capable of sustained transmission from person-to-person, and when they are introduced in populations with little or no preexisting immunity. The influenza pandemic of 1918 caused an estimated 20-40 million deaths worldwide. An avian influenza A (H5N1) virus, currently circulating in Asia, has pandemic potential. However, no evidence currently exists that a pandemic is occurring. Pharmacists are uniquely positioned to initiate nearterm practice changes that may positively impact both seasonal and potential pandemic morbidity and mortality. Pharmacists must be immunization advocates and provide pharmaceutical care that includes evaluation of immunization status. Increasing immunization to prevent invasive pneumococcal disease, as well as seasonal influenza immunization, is encouraged. A pandemic vaccine represents the most effective strategy to mitigate the effects of a pandemic. Antiviral agents represent a treatment bridge until a pandemic-specific vaccine is available. The neuraminidase inhibitors oseltamivir and zanamivir are active against H5N1, although oseltamivir resistance has been reported. Advances in vaccine research, development, and production through the use of reverse-genetics systems represent the most effective technology to rapidly produce a pandemic influenza vaccine.