Influenza vaccine is one of the least effectively utilized vaccines, perhaps because the perception of vaccination benefits is low and perceived barriers are numerous. Lay perception of the risk of contracting influenza probably is high because of the tendency to confuse the disease with other acute respiratory diseases. The perception of severity is judged to be only moderate, because most people are not familiar with the disease course in high-risk populations.

There are many perceived barriers, especially among high-risk groups for whom annual vaccination is strongly recommended. Some of the resistance stems from the side effects associated with vaccines that were used widely in the past. Another problem is the mistaken concept that influenza vaccines should prevent all winter respiratory tract illnesses. Any acute illness that is experienced in the winter following receipt of an influenza vaccine may be attributed to vaccine failure. In fact, there are other acute virus infections that cause illness in all members of the community, including those vaccinated against influenza.

One probable barrier specific to the new, live attenuated vaccine would be route of administration. People in this country are not familiar with the use of nasal drops of a live attenuated influenza virus. This concern could become problematic if recipients were to develop unrelated respiratory tract infections after vaccination via the intranasal route. They might attribute the respiratory tract illness to the administration of the vaccine. Although prelicensure clinical studies would reduce the likelihood of this complication to almost zero, recipient and provider fears on this topic might persist.

The major stumbling blocks to lay acceptance of a new influenza vaccine also apply to provider acceptance. Many physicians feel that current vaccines are not worth the effort. The low utilization of vaccine was aggravated at least for a short time by the association of Guillain-Barré syndrome with the A/New Jersey (swine-flu) vaccine. Fortunately, this association has not been found in subsequent years.

The scope and purpose of the calculations included below are described in Chapters 4 and 7. These calculations are based on certain simplifying procedures and assumptions that have been judged not to compromise their utility for the purposes of this comparison. The total costs should be taken only as an approximation of the direct cost of this disease.