Intranasal influenza vaccine: adding to the armamentarium for influenza control.

Abstract

N THE UNITED STATES, NATIONAL INFLUENZA VACCINE RECommendations have typically been based on the prevention of complications and death among high-risk persons. More recent is the increasing awareness that above and beyond the more severe individual medical consequences of influenza, enormous societal economic costs are associated with disruptions due to school and work absences and days of illness. In this issue of THE JOURNAL, Nichol et al 1 report that use of a live, attenuated influenza virus (LAIV) vaccine, administered by intranasal spray to healthy, working adults (a group without a routine recommendation to receive influenza vaccine), was followed in the subsequent influenza epidemic season by a significant reduction in severe febrile illness, days lost from work, health care visits, and the medication use that accompanies these illnesses. Are these findings important? From an individual, medical, and public health point of view, the answer is clearly yes. Reductions in febrile illnesses, defined in various ways, ranged from approximately 13% to 27%, reductions in work days lost from 18% to 28%, and reductions in health care visits from 25% to 41%. An example of the significance of influenza are the quantitative studies of the impact of influenza in the Houston, Tex, community. From 1974 to 1985, the annual infection rate was estimated at 300 per 1000 persons with approximately two thirds of these infections inducing illness. 2 Further estimates were that about 50% of those who become ill seek medical care, 1% of those who seek medical care are hospitalized, and 8% of those who are hospitalized die as a consequence of influenza. 2 These data were developed from families with young children, in which infection rates might be somewhat higher; hence, the true rates may be somewhat lower. Although these data were collected more than 10 years ago, recent reports of health care visits for febrile respiratory tract illness in 2 managed care systems during an influenza epidemic suggest that the impact of influenza in the community has not changed (W. Paul Glezen, MD,