Annual vaccination is the primary method for preventing influenza, which is associated with serious illness, hospitalizations, and even deaths among people at high risk for complications of the disease, such as pneumonia. Senior citizens are particularly at risk, as are individuals with chronic medical conditions. The Centers for Disease Control and Prevention (CDC) estimates that influenza epidemics contribute to approximately 20,000 deaths and 110,000 hospitalizations in the United States each year. Here in Oregon, and throughout the nation, influenza and pneumonia rank as the fifth leading cause of death among persons 65 years of age and older. Producing the influenza vaccine is a complex process that involves growing viruses in millions of fertilized chicken eggs. This process, which requires several steps, generally takes at least 6 to 8 months from January through August each year. Each year’s vaccine is made up of three different strains of influenza viruses, and, typically, each year one or two of the strains is changed to better protect against the strains that are likely to be circulating during the coming flu season. The Food and Drug Administration (FDA) and its advisory committee decide which strains to include based on CDC surveillance data, and FDA also licenses and regulates the manufacturers that produce the vaccine. Only three manufacturers—two in the United States and one in the United Kingdom—produced the vaccine used in the United States during the 2000-01 flu season. Like other pharmaceutical products, flu vaccine is sold to thousands of purchasers by manufacturers, numerous medical supply distributors, and other resellers such as pharmacies. These purchasers provide flu shots at physicians’ offices, public health clinics, nursing homes, and less traditional locations such as workplaces and various retail outlets. CDC has recommended October through mid-November as the best time to receive a flu shot because the flu season generally peaks from December through early March. However, if flu activity peaks late, as it has in 10 of the past 19 years, vaccination in January or later can still be beneficial. To address our study questions, we interviewed officials from the Department of Health and Human Services (HHS), including CDC, FDA, and the Health Care Financing Administration (HCFA), as well as flu vaccine manufacturers, distributors, physician associations, flu shot providers, and others. We surveyed 58 physician group practices nationwide to learn about their experiences and interviewed health department officials in all 50 states. Although the eventual supply of vaccine in the 2000-01 flu season was about the same as the previous year’s—about 78 million doses— production delays of about 6 to 8 weeks limited the amount that was available during the peak vaccination period. During the period when supply was limited and demand was higher, providers who wanted to purchase vaccine from distributors with available supplies often faced rapidly escalating prices. By December, as vaccine supply increased and demand dropped, prices declined. Last fall, fewer than 28 million doses were available by the end of October, compared with more than 70 million doses available by that date in 1999. Two main factors contributed to last year’s delay. The first was that two manufacturers had unanticipated problems growing one of the two new influenza strains introduced into the vaccine for the 2000-01 flu season. Because manufacturers must produce a vaccine that includes all three strains selected for the year, delivery was delayed until sufficient quantities of this difficult strain could be produced. The second factor was that two of the four manufacturers producing vaccine the previous season shut down parts of their facilities because of FDA concerns about compliance with good manufacturing practices, including issues related to safety and quality control. One of these manufacturers reopened its facilities and eventually shipped its vaccine, although much later than usual. The other, which had been expected to produce 12 to 14 million doses, announced in September 2000 that it would cease production altogether and, as a result, supplied no vaccine. These vaccine production and compliance problems did not affect every manufacturer to the same degree. Consequently, when a purchaser received vaccine depended to some extent on which manufacturer’s vaccine it had ordered. Purchasers that contracted only with the late- shipping manufacturers were in particular difficulty. For example, health departments and other public entities in 36 states, including Oregon, banded together under a group purchasing contract and ordered nearly 2.6 million doses from the manufacturer that, as it turned out, experienced the greatest delays from production difficulties. Some of these public entities, which ordered vaccine for high-risk people in nursing homes or clinics, did not receive most of their vaccine until December, according to state health officials. Because supply was limited during the usual vaccination period, distributors and others who had supplies of the vaccine had the ability— and the economic incentive—to sell their supplies to the highest bidders rather than filling lower-priced orders they had already received. Most of the physician groups and state health departments we contacted reported that they waited for delivery of their original lower-priced orders, which often arrived in several partial shipments from October through December or later. Those who purchased vaccine in the fall found themselves paying much higher prices. For example, one physicians’ practice in our survey ordered flu vaccine from a supplier in April 2000 at $2.87 per dose. When none of that vaccine had arrived by November 1, the practice placed three smaller orders in November with a different supplier at the escalating prices of $8.80, $10.80, and $12.80 per dose. On December 1, the practice ordered more vaccine from a third supplier at $10.80 per dose. The four more expensive orders were delivered immediately, before any vaccine had been received from the original April order. Demand for influenza vaccine dropped as additional vaccine became available after the prime period for vaccinations had passed. In all, roughly one-third of the total distribution was delivered in December or later. Part of this additional supply resulted from actions taken by CDC in September, when it appeared there could be a shortfall in production. At that point, CDC contracted with one of the manufacturers to extend production into late December for 9 million additional doses. Despite efforts by CDC and others to encourage people to seek flu shots later in the season, providers still reported a drop in demand in December. The unusually light flu season also probably contributed to the lack of interest. Had a flu epidemic hit in the fall or early winter, the demand for influenza vaccine would likely have remained high. As a result of the waning demand, manufacturers and distributors reported having more vaccine than they could sell. Manufacturers reported shipping about 9 percent less than in 1999, and more than 7 million of the 9 million additional doses produced under the CDC contract were never shipped at all. In addition, some physicians’ offices, employee health clinics, and other organizations that administered flu shots reported having unused doses in December and later. In a typical year, there is enough vaccine available in the fall to give a flu shot to anyone who wants one. However, when the supply is not sufficient, there is no mechanism currently in place to establish priorities and distribute flu vaccine first to high-risk individuals. Indeed last year, mass immunizations in nonmedical settings, normally undertaken to promote vaccinations, created considerable controversy as healthy persons received vaccine in advance of those at high risk. In addition, manufacturers and distributors that tried to prioritize their vaccine shipments encountered difficulties doing so. Flu shots are generally widely available in a variety of settings, ranging from the usual physicians’ offices, clinics, and hospitals to retail outlets such as drugstores and grocery stores, workplaces, and other convenience locations. Millions of individuals receive flu shots through mass immunization campaigns in nonmedical settings, where organizations, such as visiting nurse agencies under contract, administer the vaccine. The widespread availability of flu shots may help increase immunization rates overall, but it generally does not lend itself to targeting vaccine to high- priority groups. The timing of some of the mass immunization campaigns last fall generated a great deal of controversy. Some physicians and public health officials were upset when their local grocery stores, for example, were offering flu shots to everyone when they, the health care providers, were unable to obtain vaccine for their high-risk patients. Examples of these situations include the following: A radio station in Colorado sponsored a flu shot and a beer for $10 at a local restaurant and bar—at the same time that the public health department and the community health center did not have enough vaccine. One grocery store chain in Minnesota participated in a promotion offering a discounted flu shot for anyone who brought in three soup can labels. Flu shots were available for purchase to all fans attending a professional football game. CDC took some steps to try to manage the anticipated vaccine delay by issuing recommendations for vaccinating high-risk individuals first. In July 2000, CDC recommended that mass immunization campaigns, such as those open to the public or to employee groups, be delayed until early to mid-November. CDC issued more explicit voluntary guidelines in October 2000, which stated that vaccination efforts should be focused on persons aged 65 and older, pregnant women, those with chronic health conditions that place them at high risk, and health care workers. The October guidelines also stated that while efforts should be made to increase participation in mass immunization campaigns by high-risk persons and their household contacts, other persons should not be turned away. Some organizations that conducted mass immunizations said they generally did not screen individuals who came for flu shots in terms of their risk levels. Some said they tried to target high-risk individuals and provided information on who was at high risk, but they let each person decide whether to receive a shot. Their perspective was that the burden lies with the individual to determine his or her own level of risk, not with the provider. Moreover, they said that the convenience locations provide an important option for high-risk individuals as well as others. Health care providers in both traditional and nontraditional settings told us that it is difficult to turn someone away when he or she requests a flu shot.