A prospective study on the efficacy of two-dose influenza vaccinations in cancer patients receiving chemotherapy.

Abstract

Cancer patients receiving chemotherapy are at risk of acquiring influenza infections. Two-dose vaccination is a proposed strategy for increasing vaccination efficacy; however, this has yet to be confirmed in this population. The purpose of this study was to clarify the efficacy and safety of this strategy. We conducted a multicentre prospective study on a two-dose vaccination regimen in cancer patients receiving chemotherapy. Second vaccinations were performed in patients who did not respond to all three viral strains after the first vaccination. Serum haemagglutination inhibition titres were measured to determine the patients' immunological response, 2 weeks prior to the first vaccination, 3-5 weeks after each vaccination, and at the end of the influenza season. We enrolled 109 patients, including 70 with solid tumours, 36 with haematological malignancies, and 3 with both cancer types. Among the total patients, the proportion of patients with protective titres against the three viral strains increased significantly from 3 to 27% (P < 0.01) following vaccination. Among the 79 patients who received a second vaccination, the proportion of those with protective titres against the individual strains increased by 10% (H1N1), 8% (H3N2), and 3% (B) compared with after the first vaccination. Serious adverse events were not observed. We recommend influenza vaccinations for cancer patients, including those receiving chemotherapy. Also, the additional benefit of the second vaccination may be limited.