Influenza Prevention and Treatment: Current Practices and New Horizons

• Influenza vaccine
• Influenza A virus, human
• Influenza B virus
• Neuraminidase inhibitors
• Amantadine
• Rimantadine

Significant new tools to prevent and treat influenza will become available to clinicians in 1999/2000, and additional advances in vaccine are on the horizon. Advances include new antiviral compounds to treat influenza and new vaccines to prevent the disease. The development of these tools is a direct result of advances in fundamental influenza virology research.

We now understand that both influenza A and influenza B viruses have eight genetic segments that encode 10 proteins. Researchers have also elucidated the functions of these proteins. Immunity to influenza in humans is primarily mediated by secretory IgA and serum IgG antibodies directed against the two surface proteins: hemagglutinin and neuraminidase. Hemagglutinin attaches viruses to cells, and neuraminidase is responsible for releasing virus from infected cells. Antibodies directed against these proteins disrupt two key functions of viral replication. Induction of antibodies with standard inactivated influenza vaccine prevents influenza in adults and children. It is estimated that up to 90 million doses of the inactivated vaccine will be used in the United States this year (1). The vaccine has an estimated efficacy of 70% to 90% in adults but is less efficacious in elderly persons because this group may not respond with vigorous antibody responses.

Inactivated influenza vaccine can prevent much of the illness and death caused by influenza. The vaccine is recommended for all persons who are at high risk for serious complications from influenza, including all persons 65 years of age or older and persons of any age who have underlying chronic disease that predisposes them to death from influenza. The latter category includes persons with heart disease, lung disease, chronic renal disease, diabetes, immunosuppression, and severe chronic anemia and residents of nursing homes or other long-term care facilities. To protect persons with underlying medical conditions who are living at home, everyone …