Immunogenicity of low-dose MF59-adjuvanted 2009 influenza A/H1N1 vaccine in dialysis patients.

BACKGROUND

In response to the pandemic 2009 A/H1N1 virus, monovalent MF59-adjuvanted vaccines were prepared. Recently, single 3.75-μg doses of MF59-adjuvanted vaccines have shown good immunogenicity in young adults. However, the immunogenicity of these vaccines has not been evaluated in dialysis patients.

METHODS

Dialysis patients received a single 3.75-μg dose of MF59-adjuvanted vaccine by intramuscular injection. For immunogenicity assays, serum samples were obtained before vaccination and 28 days after vaccination. All sera were tested by hemagglutination inhibition assays.

RESULTS

Overall, 48 hemodialysis (HD) patients and 34 peritoneal dialysis (PD) patients were included in immunogenicity analysis. In HD patients, geometric mean titers (GMTs) were significantly increased compared with baseline GMTs in both young (aged 18-60 years) and elderly (aged ≥ 60 years) patients (51.2 ± 51.4 vs. 14.1 ± 20.7 in young patients, P = 0.012; 37.9 ± 73.9 vs. 6.8 ± 8.0 in elderly patients, P = 0.018, respectively). The rates of seroprotection and seroconversion were 27.6 and 17.2 % in young patients and 31.6 and 26.3 % in elderly patients, respectively. Among PD patients, GMTs were increased only in young patients (39.8 ± 51.4 vs. 6.8 ± 5.0, P = 0.001). The rates of seroprotection and seroconversion were 36.0 and 36.0 % in young patients and 11.1 and 0.0 % in elderly patients, respectively.

CONCLUSION

A single 3.75-μg dose of MF59-adjuvanted vaccine was suboptimal to elicit protective antibody response in dialysis patients. Antibody responses against vaccine were compromised especially in elderly PD patients. Trials of different vaccination protocols such as a two-dose schedule or a higher hemagglutinin antigen dose of MF59-adjuvanted vaccine are necessary for improving antibody response in dialysis patients.