Annual influenza vaccination: immune response in patients over 10 years.

OBJECTIVE

To determine the effect of repeated annual influenza immunization on the host's serum antibody.

DESIGN

Ten year observational study with cohort design.

SETTING

Cystic Fibrosis Center at St. Vincent's Hospital and Medical Center, New York City, NY.

PATIENTS

Thirty-eight children and young adults with cystic fibrosis (CF).

MEASUREMENTS

Serum hemagglutination inhibition (HI) antibody titers were determined at the time of vaccination and 4 weeks later each year in the fall before the influenza epidemic. Shwachman scores were determined each year.

RESULTS

While the pre-vaccination and post-vaccination geometric mean serum HI antibody titers varied from year to year, no upward or downward trend was evident over the 10 year period. The reciprocal of the post-vaccination geometric mean HI titers ranged annually from 32 to 74 for the influenza A (H3N2) vaccine strains, from 53 to 133 for the influenza A (H1N1) strains, and from 18 to 174 for influenza B strains. In addition, the majority of vaccinees had a presumably protective post-vaccination serum HI titer > or = 1:40 each year for all three vaccine strains. The initial mean Shwachman score of the group was 77. The final score of 76 after 10 years was not significantly different.

CONCLUSIONS

Annual influenza vaccination appears to regularly induce presumably protective serum antibody levels in most CF children and young adults studied over a 10 year period.