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Evaluation of the antibody responses induced by the 2006–2007 influenza vaccine

Abstract number: 1732_228

Chan Y.-J., Hwang S.-J., Lin J.-C., Tsai C.-H., Liu C.-Y., Lee S.-D., Ho D.M., Lee C.-H.

Objectives: Although influenza (Flu) is an old infectious disease, it will cause pandemics and requires global cooperation for control and prevention. In addition to the avoidance of exposure during the influenza season vaccination has been the most effective modality for preventing influenza epidemics. However, due to the genetic variability of the influenza it requires vaccination every year. Our Department of Health supported free influenza vaccination for aged people (>65 year-old) for years and the host antibody responses are evaluated.

Methods: A total of 89 paired sera was collected before and 3 weeks after the vaccination with one dose of a commercial trivalent influenza vaccine for 2006–2007. The paired samples were tested for influenza A and B antibodies by complement fixation (CF) and quantitative enzyme-linked immunosorbent assay (ELISA). In addition, 83 paired sera were tested by haemagglutination inhibition (HI) using an A/New Caledonia/20/99-like strain. There were 49 males and 34 females, and 47 people were older than 65.

Results: Our results indicated that the CF response rates (defined as 4-fold titer increase of the paired sera) for both influenza A and B were low (33.7% and 15.7%, respectively). However, the pre-immunised ELISA titers for both influenza A and B were much higher than normal (average 98.3±45.6 RU/mL for Flu A and 176±57.5 RU/mL for Flu B; normal <22 RU/mL). The overall response rate for HI was 32.5% (27/83), but the response rate of the aged (>65 year-old) was lower (27.7%, 13/47) than people <65 year-old (38.9%, 14/36). However, the rate of pre-immunised sera with protective HI titer (HI ≥ 40) was 80.7% (67/83).

Conclusion: The antibody responses induced by the 2006–2007 influenza vaccine were low, but the pre-immunised antibody positive rates and titers were high. The phenomenon might reflect the quality of the vaccine and the consequences of previous vaccination.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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