Al (FEDER). Dr. M. Herna dez-Guerra is the recipient Funding: This study has been supported in part by grants from Fonds Europe de De ?of a grant from Instituto de Salud Carlos III (538/07) and Programa de Intensificacion de Actividad Investigadora (INT07/173). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected] who care for patients with chronic digestive disease were recommended by the World Health Organization to encourage patients to receive the novel (H1N1) influenza A vaccine during the global pandemic of 2009. The recommendations concerned elderly patients (.65 years) and those with chronic medical conditions or immunosuppression [1], considered to be at high risk of developing influenza-related complications [2]. The latter conditions are important in chronic hepatitis C (CHC) patients, especially those receiving standard medical treatment (pegylated-interferon and ribavirin). Indeed, hepatologists are aware that CHC patients may experience bacterial infectionsduring pegylated-interferon based regimens related or not to neutropenia[3?]. During the 2009 (H1N1) influenza A virus outbreak, scarce data were available to reassure CHC patients regarding tolerance and serological response to the vaccine. This provoked anxiety in patients potentially at risk of severe infection and even among physicians without guidelines to follow. In addition, CHC patients with ongoing pegylated-interferon based therapy may have a lower immunogenic response [7] and experience side effects that may be aggravated by vaccination adverse effects, thus compromising CHC treatment adherence. Therefore, the present study was conducted to evaluate the (H1N1) influenza A virus vaccine immunogenic response in CHCInfluenza A Vaccine in Chronic Hepatitis Cpatients with and without ongoing standard medical treatment and compared it with that of healthy subjects. Recently, a lower immunogenic response has been found in pediatric patients with inflammatory bowel disease (IBD) under immunosuppression therapy [8]. Therefore, an additional group of patients with IBD were included. In addition, 1317923 perception and acceptance of influenza vaccination was assessed using a validated outcome questionnaire designed for this purpose [9].Methods Ethics StatementPatients and a group of healthy volunteer get Lecirelin healthcare workers were 69-25-0 custom synthesis invited to participate and enrolled after written informed consent was obtained. Approval for the study protocol was obtained from the national Agencia Espanola del Medicamento y Productos Sanitarios and local ethics committee (Hospital Universitario de Canarias), and the study was conducted in accordance with the principles of the 1975 Declaration of Helsinki.The standard antigen was diluted to contain four hemagglutinin units and back titration was performed. Two-fold serial dilution of RDE-treated sera was performed in v-bottom microtiter plates. Then, diluted sera were mixed with 25 ml of H1N1pdm antigen (2010?011 World Health Organization influenza reagent kit for identification of influenza isolates). After 1 hour incubation at room temperature, 50 ml of red blood cell (diluted 0.05 in PBS) was added to the wells. Positive and negative serum controls were included for each plate. Titers were expressed as the reciprocal of the highest dilution.Al (FEDER). Dr. M. Herna dez-Guerra is the recipient Funding: This study has been supported in part by grants from Fonds Europe de De ?of a grant from Instituto de Salud Carlos III (538/07) and Programa de Intensificacion de Actividad Investigadora (INT07/173). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected] who care for patients with chronic digestive disease were recommended by the World Health Organization to encourage patients to receive the novel (H1N1) influenza A vaccine during the global pandemic of 2009. The recommendations concerned elderly patients (.65 years) and those with chronic medical conditions or immunosuppression [1], considered to be at high risk of developing influenza-related complications [2]. The latter conditions are important in chronic hepatitis C (CHC) patients, especially those receiving standard medical treatment (pegylated-interferon and ribavirin). Indeed, hepatologists are aware that CHC patients may experience bacterial infectionsduring pegylated-interferon based regimens related or not to neutropenia[3?]. During the 2009 (H1N1) influenza A virus outbreak, scarce data were available to reassure CHC patients regarding tolerance and serological response to the vaccine. This provoked anxiety in patients potentially at risk of severe infection and even among physicians without guidelines to follow. In addition, CHC patients with ongoing pegylated-interferon based therapy may have a lower immunogenic response [7] and experience side effects that may be aggravated by vaccination adverse effects, thus compromising CHC treatment adherence. Therefore, the present study was conducted to evaluate the (H1N1) influenza A virus vaccine immunogenic response in CHCInfluenza A Vaccine in Chronic Hepatitis Cpatients with and without ongoing standard medical treatment and compared it with that of healthy subjects. Recently, a lower immunogenic response has been found in pediatric patients with inflammatory bowel disease (IBD) under immunosuppression therapy [8]. Therefore, an additional group of patients with IBD were included. In addition, 1317923 perception and acceptance of influenza vaccination was assessed using a validated outcome questionnaire designed for this purpose [9].Methods Ethics StatementPatients and a group of healthy volunteer healthcare workers were invited to participate and enrolled after written informed consent was obtained. Approval for the study protocol was obtained from the national Agencia Espanola del Medicamento y Productos Sanitarios and local ethics committee (Hospital Universitario de Canarias), and the study was conducted in accordance with the principles of the 1975 Declaration of Helsinki.The standard antigen was diluted to contain four hemagglutinin units and back titration was performed. Two-fold serial dilution of RDE-treated sera was performed in v-bottom microtiter plates. Then, diluted sera were mixed with 25 ml of H1N1pdm antigen (2010?011 World Health Organization influenza reagent kit for identification of influenza isolates). After 1 hour incubation at room temperature, 50 ml of red blood cell (diluted 0.05 in PBS) was added to the wells. Positive and negative serum controls were included for each plate. Titers were expressed as the reciprocal of the highest dilution.