Efficacy of influenza vaccine among geriatric inpatients: effect of previous vaccination and antibody induction by single and twice injections

H. Ikematsu, A. Nabeshima, K. Yamaji, Y. Chong, W. Li, J. Hayashi, S. Goto, T. Oka, T. Shirai, S. Kashiwagi

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To investigate the effect of previous influenza vaccination and the difference in antibody induction by single and twice injection of influenza vaccine in the elderly, hemagglutination inhibition (HI) antibody titers of the three types of influenza viruses were measured. Influenza vaccination was done for 217 inpatients. For the patients who had influenza vaccination in the year prior to the study, influenza vaccine was administered once to 77 patients and twice to another 70 patients. Influenza vaccine was injected twice to 70 patients who had not received influenza vaccine in the previous years. The influenza vaccine induced an increase in HI titer in almost all patients. The geometric mean of the HI titer and the frequency of patients with HI titers over 128x were similar after vaccination in the groups of patients who were injected twice, irrespective of whether or not influenza vaccination was given in the year prior to the study. The geometric means of the HI titers for influenzas A/H3N2 and B and the frequency of HI titers over 128x for influenza A/H3N2 after vaccination were lower in the patients who received vaccine once than in the patients vaccinated twice. These results suggest that prior vaccination does not diminish antibody response to influenza vaccine significantly in the elderly when influenza vaccine is injected twice. Although single injection is inferior to twice injection in antibody induction with some vaccine virus strains, induction of HI titers over 128x is found in more than 70% of elderly. Single injection of influenza vaccine may be practically effective and useful for protection of influenza infection in the elderly.

Original languageEnglish
Pages (from-to)1042-1047
Number of pages6
JournalKansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases
Issue number10
Publication statusPublished - Oct 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Medicine(all)


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