Influenza immunization in nursing homes: who does not get immunized and whose status is unknown?

Objective: To identify nursing home resident and facility characteristics associated with patients not receiving influenza immunization and having unknown immunization status.
Design: Secondary data analysis using multinomial logistic regression of data from the National Nursing Home Survey, a nationally representative establishment-based survey.
Setting: A total of 1,423 nursing facilities of all ownerships and certifications systematically sampled with probability proportional to number of beds.
Patients: A total of 7,350 randomly sampled people aged 65 years or older residing in nursing homes between July and December 1999 (approximately 6 per facility).
Main Outcome Measure: Immunization status of residents.
Results: Fifteen percent of residents were not immunized and 19% had unknown immunization status. In multivariate analysis, lack of immunization and unknown immunization status were each separately associated with being newly admitted, with no or unknown pneumococcal immunization, and with facility failures to screen for immunization and to record inoculation in the medical record. High-risk status and staff immunization requirements had no effect. Separate analyses showed that residents with unknown immunization status are statistically significantly different from both those vaccinated and those not vaccinated.
Conclusion: This study indicates that both resident and facility characteristics are associated with failure to be immunized for influenza. Facilities should consider targeting younger, newly admitted, and residential care residents for influenza immunization, since they are more likely to be missed. Further research into the barriers to immunization specific to nursing home resident choice or opportunity may be warranted.