Table 1 Hospitalization rates for acute respiratory disease in patients with and without chronic conditions Hospitalizations per Population Year of study Age 100,000 persons with high-risk conditions HealthMaintenance 1968–1969, 15–44 years 56–110 Organizations 1970–1971, 45–64 years 392–635 (Barker et al 1980) 1972–1973 ≥65 years 399–518 Hospitalizations per 100,000 persons without high-risk conditions 23–25 13–23 - 1973–1993 1992–1997 1992–1997 1978–1981 0–11 months 2–4 years 5–17 years 0–1 years 2–4 years 5–17 years 0–1 years 2–4 years 5–17 years All ages 1900 800 320 92 1181 713 386 772 458 216 197 496–1038 196 86 41 231 53 19 193 21 16 93 Plans-Rubió TennesseeMedicaid (Neuzil et al 2000) Kaiser Permanente (Izurieta et al 2000) Group Health Cooperative (Izurieta et al 2000) Population of Houston (Glezen et al 1987) in healthy and high-risk persons aged 6 months, while LAIV is approved for use in healthy persons aged 5–49 years. Since 1976, inﬂuenza vaccines contain one three viral strains: inﬂuenza A (H3N2) virus, one A (H1N1) virus, and one B virus. Recommended composition of the inﬂuenza vaccine for use in the 2006–07 inﬂuenza season include the following viral strains: A/New Caledonia/20/99 (H1N1), A/ Wisconsin/67/2005 (H3N2), B/Malaysia/2506/2004 (WHO 2006). Both vaccines stimulate host response to the antigenic determinants on the viral surface. Each year, one or more virus strains might be changed on the basis of global surveillance for inﬂuenza viruses and the emergence and spread of new strains. Vaccines should be administered annually to provide optimal protection against inﬂuenza because inﬂuenza antigens change progressively with time, so that vaccination against one strain could provide little or no protection against new strains. Inactivated and live attenuated inﬂuenza vaccine should not be administered to persons known to have anaphylactic hypersensitivity to eggs or to other components of the vac- cine without ﬁrst consulting a physician. Prophylactic use of antiviral agents is an option for preventing inﬂuenza among such persons. Persons who have a history of anaphylactic hypersensitivity to vaccine components but who are also at high risk for complications from inﬂuenza can beneﬁt from vaccine after appropriate allergy evaluation and desensitiza- tion. Persons with acute febrile illness usually should not be vaccinated until their symptoms have abated. However, minor illnesses with or without fever do not contraindicate use of inﬂuenza vaccine. 46 The most frequent side effect of inactivated inﬂuenza vaccina- tion is soreness at the injection site that lasts 1–2 days. Immediate reactions (eg, hives, angioedema, allergic asthma, and systemic anaphylaxis) rarely occur after inﬂuenza vaccination. These re- actions probably result from hypersensitivity to certain vaccine components; the majority of reactions probably are caused by residual egg protein. Fever, tiredness, muscle aches, and other systemic symptoms can occur after vaccination with inacti- vated vaccine and most often affect persons who have had no previous exposure to the inﬂuenza virus antigens in the vaccine. Local reactions typically are mild and rarely interfere with the person’s ability to conduct usual daily activities. One blinded, randomized, cross-over study among 1952 adults and children with asthma, demonstrated that only body aches were reported more frequently after inactivated inﬂuenza vaccine (25.1%) than placebo-injection (20.8%) (ALAACRC 2001). One study reported 20%–28% of children with asthma aged 9 months–18 years with local pain and swelling (Park et al 1996). Wright and colleagues (1977) reported no difference in local reactions among 53 children aged 6 months–6 years with high-risk medi- cal conditions or among 305 healthy children aged 3–12 years in a placebo-controlled trial of inactivated inﬂuenza vaccine. In a study of 12 children aged 5–32 months, no substantial local or systemic reactions were noted (Piedra et al 1993). The use of a swine inﬂuenza inactivated vaccine in 1976 was associated with an increased frequency of Guillain-Barré syndrome (Schonberger et al 1979). The rate of persons affected by this medical problem was 1 per 120,000 vac- cines. Nevertheless, this side-effect has not been observed International Journal of COPD 2007:2(1)