Effect of 25-hydroxyvitamin D status on serological response to influenza vaccine in prostate cancer patients

Background Epidemiologic data suggest that there is an association between vitamin D deficiency and influenza infection. We conducted a prospective influenza vaccination study to determine the influence of vitamin D status on serological response to influenza vaccine in prostate cancer (CaP) patients. Methods During the 2006-2007 influenza season, CaP patients treated at Roswell Park Cancer Institute were offered vaccination with the trivalent influenza vaccine (Fluzone^®, 2006-2007) and sera collected for hemagglutination inhibition (HI) assay titers before and 3 months after vaccination. Response to vaccination was defined as ≥1:40 titer ratio or a fourfold increase in titer at 3 months, against any of the three strains. Serum 25-hydroxyvitamin D (25-D₃) levels were measured using DiaSorin ¹²⁵I radioimmunoassay kits. Results Thirty-five patients with CaP participated in the study. Median baseline 25-D₃ level was 44.88 ng/ml (range: 9.16-71.98 ng/ml) Serological response against any of the three strains was noted in 80%. There was a significant effect of baseline 25-D3 level when tested as a continuous variable in relation to serological response (P = 0.0446). All patients in the upper quartile of 25-D3 level responded by mounting a serological response (P = 0.0344). None of the other baseline variables (age, race, chemotherapy status, or white cell count) had an effect on serological response. Conclusions In this study in CaP patients, a replete vitamin D status was associated with more frequent serological response to influenza vaccine.