Influenza remains a global cause of high levels of morbidity and mortality. Older individuals and those with high-risk conditions are most likely to experience adverse outcomes. Several recent studies have confirmed the clinical effectiveness as well as the economic value of inactivated influenza vaccines in preventing hospitalization, and in some cases deaths, in this group. Respiratory syncytial and parainfluenza viruses can produce severe illness in the very young. Vaccine development continues, but the most immediate preventive approach involves the use of immune globulin in high-risk, pre-term children. The causal agent of the regional disease, hantavirus pulmonary syndrome, has been named and risk factors for its acquisition further defined. This emerging infection, as well as others which are more regular in their occurrence, demonstrate the need for good surveillance mechanisms.