Influenza Vaccine Failure Associated With Age And Immunosuppression

Background. The influenza vaccine is one of the best ways to prevent influenza infection, but little is known about influenza vaccine failure.Methods. This study evaluated patients admitted for acute respiratory illness during 2015-2019 influenza seasons to compare vaccinated influenza-negative to vaccinated influenza-positive patients. Statistical analyses were performed with STATA and R using Pearson chi(2), Kruskal-Wallis, Wilcoxon rank-sum tests, and multivariate logistic regression.Results. Of 1236 enrolled patients vaccinated for influenza, 235 (19%) tested positive for influenza. Demographics, vaccines, and comorbidities were similar between groups except for morbid obesity (13% influenza negative vs 8%, P = .04), and immunosuppression (63% influenza positive vs 54%, P = .01). Logistic regression analysis demonstrated older patients (odds ratio [OR], 1.47; 95% confidence interval [CI], 1.03-2.10) and immunosuppressed patients (OR, 1.56; 95% CI, 1.15-2.12) were at increased risk for influenza despite immunization. When evaluated by influenza subtype, immunosuppression increased the risk for influenza A/H3N2 (OR, 1.86; 95% CI, 1.25-2.75).Conclusions. Our study demonstrated increased risk of influenza vaccine failure in older patients and immunosuppressed patients. These groups are also at increased risk for influenza complications. To improve protection of patients against influenza illnesses, more effective vaccines and strategies are needed.