1. 1) SugiuraA, YanagawaH, EnomotoC, et al.: A field trial for evaluation of the prophylactic effect of influenza vaccine containing inactivated A2/Hong Kong and B influenza vaccines. J Infect Dis., 1970; 122: 472-478.
2. 2) NicholKL, MargolisKL, WuorenmaJ, et al.: The efficacy and cost effectiveness of vaccination against influenza among elderly persons living in the community. N Engl J Med., 1994; 331: 778-784.
3. 3) GovaertTM, ThijinCT, MasurelN, et al.: The efficacy of influenza vaccination in elderly individuals. JAMA, 1994; 272: 1661-1665.
4. 4) ArnoldS: The clinical efficacy of influenza vaccination. Pharmaco Economics, 1996; 9 Suppl. 3: 16-22.
5. 5) GrossPA, HermogenesAW, SacksHS, et al.: The efficacy of influenza vaccine in elderly person: a meta-analysis and review of the literature. Ann Intern Med., 1995; 123: 517-527.