A prospective, comparative study of the immune response to inactivated influenza vaccine in pediatric liver transplant recipients and their healthy siblings.
BACKGROUND
Annual influenza vaccination is routinely recommended for pediatric solid organ transplant recipients. However, there are limited data defining the immune response to the inactivated vaccine in this population.


METHODS
This prospective study compared the humoral and cell-mediated immune responses to the trivalent subvirion influenza vaccine in pediatric liver transplant recipients with those in their healthy siblings. All subjects received inactivated influenza vaccine. Hemagglutination inhibition and interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot assays for New Caledonia and Shanghai strains were performed at baseline, after each vaccine dose, and 3 months after the series. Seroconversion was defined as a 4-fold increase in antibody titers; seroprotection was defined as an antibody titer > or =1:40. An increase in the number of T cells secreting IFN-gamma was considered to be a positive enzyme-linked immunosorbent spot response.


RESULTS
After 1 dose of vaccine, transplant recipients achieved rates of antibody seroprotection and seroconversion that were similar to those achieved by their healthy siblings. However, for both influenza strains, IFN-gamma responses by enzyme-linked immunosorbent spot were significantly attenuated in transplant recipients after 2 doses of vaccine. No cases of influenza or vaccine-related serious adverse events were documented in the study.


CONCLUSIONS
The diminished cell-mediated immune response to influenza vaccination that was observed in pediatric liver transplant recipients suggests that the current vaccine strategy may not provide optimal protection. Because of concerns regarding potential emergence of more virulent influenza strains, further studies are warranted to determine if IFN-gamma responses are predictive of efficacy and to identify the optimal vaccination strategy to protect populations with a high risk of infection.
Madan
Rebecca Pellett
RP
Department of Pediatrics, Mount Sinai School of Medicine, New York, New York, USA. rmadan@aecom.yu.edu
Tan
Maria
M
Fernandez-Sesma
Ana
A
Moran
Thomas M
TM
Emre
Sukru
S
Campbell
Andrew
A
Herold
Betsy C
BC
D000293:Adolescent; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007111:Immunity, Cellular; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D009981:Influenza B virus / Q000276:immunology; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control; D007371:Interferon-gamma / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000276:immunology; D017093:Liver Failure / Q000276:immunology*; D008297:Male; D011446:Prospective Studies; D035781:Siblings; D013601:T-Lymphocytes / Q000276:immunology; D014180:Transplantation; D015164:Vaccines, Inactivated / Q000276:immunology
D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated; D007371:Interferon-gamma