Persistence of influenza vaccine-induced antibodies in lung transplant patients between seasons

Abstract

Immunization policy-making bodies advised against immunizing too early before the influenza season because vaccine-specific antibody may wane before the end of the influenza season. Lung transplant patients are included in the group of high-risk patients for whom this recommendation had been made. We hypothesized that immunosuppressed lung transplant patients would maintain protective concentrations of influenza antigen-specific antibodies between seasons. As part of a planned 5-year study of influenza vaccine responses in lung transplant patients, we measured influenza antibody concentrations by hemagglutination inhibition assay before influenza immunization annually. The fraction of lung transplant patients who maintained seroprotective levels (≥ 40 hemagglutination units) approximately 11 months from last season immunization was calculated. Antibody concentrations and response rates in lung transplant patients were compared with healthy individuals and those waiting for lung transplantation. The majority of lung transplant patients maintained seroprotective influenza antigen-specific antibody concentrations for approximately 11 months after immunization. Seroprotection rates varied greatly with influenza antigens (healthy 68-100%, pretransplant 44-100%, transplant 64-100%), and were similar when groups were compared. More than 70% of lung transplant patients maintained seroprotective antibody concentrations to 10 of 11 vaccine antigens. Seroprotective influenza antibody concentrations are maintained at very high rates among immunosuppressed lung transplant patients and depend more on the vaccine virus than the immunostatus of the vaccine recipient. Early seasonal influenza immunization of lung transplant patients is appropriate.