The effect of hepatitis C virus infection on serologic response to influenza vaccine

Background. People infected with hepatitis C virus (HCV) have impaired serologic response to hepatitis B vaccination. The biologic mechanism for the impaired response is unknown and it is unknown if hepatitis C infection is associated with impaired response to other vaccines.; Main objective. To compare serologic responses to the trivalent inactivated influenza vaccine (TIV) in HCV antibody negative with HCV infected persons.; Secondary objectives. To assess the effect of HCV treatment, age, body mass index, smoking and prevaccination antibody titers on serologic responses to the TIV.; Methods. Volunteers were recruited among veterans about to receive the TIV at the Baltimore Veterans Hospital. Twenty HCV antibody negative, 41 HCV infected and 28 HCV-infected persons being treated with interferon and ribavirin were recruited.; Serum samples for HAI titers were obtained before vaccination and 4-6 weeks after vaccination.; Results. Seroprotection rates (percentage of persons with postvaccination HAI titers ≥ 40) between HCV antibody negative and HCV infected persons were 85% versus 66% against H1N1 (p=0.14), 95% versus 90% against H3N2 and 90% versus 59% against B (p=0.01). Seroprotection rates were associated with prevaccination HAI titers. Protective HAI titers were achieved in the following persons: 27% with prevaccination HAI titers of 4; 46% with prevaccination titers of 8; 55% with prevaccination titers of 16 and 76% with prevaccination titers of 32.; Serologic response rates (percentage of persons with four-fold rises in antibody titers) were similar between HCV antibody negative and HCV infected persons. Serologic response rates were inversely related to prevaccination antibody titers. Seroprotection rates were not statistically significantly different for HCV infected persons who received anti-HCV therapy compared to HCV infected persons who did not receive therapy.; Conclusions. (1) Following administration of the TIV, HCV-infected persons had lower seroprotection rates against influenza B compared to HCV-antibody negative persons. (2) Seroprotection following vaccination was related to pre-vaccination antibody titers. (3) Serologic response rates were similar between HCV antibody negative and HCV infected individuals. (4) Concurrent HCV treatment with interferon and ribavirin had a moderate effect in improving seroprotection rates against H1N1. (5) Among HCV infected persons age was inversely related to seroprotection against H1N1.