Does Vitamin D Deficiency Affect the Immunogenic Responses to Influenza Vaccination? A Systematic Review and Meta-Analysis.

Influenza virus infection is a major global public health problem, and the efficacy of influenza vaccination is not satisfactory. Vitamin D is involved in many immune-mediated inflammatory processes. The impact of vitamin D levels on the immunogenic response to influenza vaccination is not clear. We performed a comprehensive literature search and systematic review of studies that investigated vitamin D and influenza vaccination. Data pertaining to study population, vaccine components, vitamin D levels, and immunogenic response were analyzed. Nine studies, with a combined study population of 2367 patients, were included in the systematic review. Four studies were included in the meta-analysis to investigate the influence of vitamin D deficiency (VDD) on the seroprotection (SP) rates and seroconversion (SC) rates following influenza vaccination. We found no significant association between vitamin D level and the immunogenic response to influenza vaccination. However, strain-specific differences may exist. We observed lower SP rates of influenza A virus subtype H3N2 (A/H3N2) and B strain in VDD patients than patients with normal vitamin D levels (A/H3N2: 71.8% vs. 80.1%, odds ratio (OR): 0.63, 95% confidence interval (CI): 0.43-0.91, p = 0.01; B strain: 69.6% vs. 76.4%, OR: 0.68, 95% CI: 0.5-0.93, p = 0.01). However, the SP rates of A/H1N1 and SC rates of all three strains were not significantly different in VDD and control groups. In conclusion, no association was observed between VDD and immunogenic response to influenza vaccination.

Antibody and cell-mediated immune response to whole virion and split virion influenza vaccine in patients with inflammatory bowel disease on maintenance immunosuppressive and biological therapy.

OBJECTIVE: Influenza vaccination is recommended for inflammatory bowel disease (IBD) patients on immunosuppressive therapy. The objective was to evaluate the antibody and cell-mediated immune response to the split and whole virion influenza vaccine in patients with IBD treated with anti-TNF-α and immunosuppressive therapy. PATIENTS AND METHODS: One hundred and fifty-six immunocompromised IBD patients were vaccinated. Fifty-three patients (control group) refused vaccination. Split virion vaccine and whole virion vaccine were used. Serum samples were obtained for pre- and postimmunization antibody titers to influenza vaccine (A/California/7/2009 [H1N1], A/Victoria/361/2011 [H3N2], B/Wisconsin/1/2010-like B/Hubei-Wujiagang/158/2009). Cell-mediated response was evaluated using an interferon (INF)-γ, interleukine (IL)-2 and tumor necrosis factor (TNF)-α ELISA. RESULTS: Postimmunization titers of both influenza subtypes increased significantly after the administration of split virion vaccines compared to the controls and to those who received whole virion vaccine. The antibody titers of Influenza B also increased significantly in patients immunized with split vaccine and treated with anti-TNF-α therapy. After influenza vaccination, the level of serum IL-2 significantly decreased. No serious side effects developed occurred after influenza vaccination, and the influenza-like symptoms did not differ significantly between vaccinated versus control patients. The relapse of the disease was observed in only 10% of the patients and was more common in vaccinated than in control subjects. CONCLUSION: Split virion vaccines seem to be more effective than whole virion vaccines. Measuring the antibody responses is worthwhile in patients treated with immunosuppressants to determine the efficacy of influenza vaccination.