Despite the best efforts of pharmacists and other healthcare professionals, not enough older adults get seasonal influenza vaccines (SIVs) in the United States and Canada, according to a new study.

The report, published in Gerontology & Geriatric Medicine, points out that vaccine rates among the elderly remain suboptimal despite the availability of a universal influenza-vaccination program in both nations.

University of Manitoba–led researchers sought to better understand the factors that determine flu vaccine uptake so that more effective interventions can be developed.

To do that, the study team evaluated the determinants of SIV uptake in elderly patients in the U.S. and Canada by systematically searching relevant bibliographic databases and websites from 2000 to 2017 for population-based clinical trials or observational studies conducted in community-based elderly individuals.

Then, two reviewers independently screened the identified citations for eligibility using a two-stage process to review the title/abstract and full-text article. Data were collected on determinants of uptake (i.e., any vaccine receipt) and adherence (defined as receipt of vaccine in more than one season) to seasonal influenza vaccination. Ultimately, five U.S. cross-sectional studies on SIV uptake, although none on adherence, met the eligibility criteria.

Results indicate that the following factors were associated with increased uptake of seasonal influenza vaccine:
• Older age (pooled odds ratio [POR] = 1.44, 95% CI = 1.11, 1.86);
• White race (POR = 1.33, 95% CI = [1.10, 1.64]); having higher income (POR = 1.06, 95% CI = [1.04, 1.09]); and
• Health insurance (POR = 1.40, 95% CI = [1.25, 1.55]).

“Older, ethnically white, higher income elderly individuals with access to health insurance coverage and a regular health care provider have higher SIV uptake in the United States,” the study authors conclude. “There was limited evidence for other socioeconomic and health-related determinants. Further studies are needed to provide an evidence base for planning more effective influenza vaccination programs in the United States.”

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