The Effect of T Cell Activation on the Immune Responses to Hepatitis A Vaccine in Children with Obesity: A Preliminary Study

Background: Obesity is a chronic inflammation, effects immune dysregulation. Hepatitis A vaccine (HAV) are recommended in obesity with NAFLD. Previous studies reported that obesity had poor immune response to live vaccine. There is limited data on live attenuated HAV, especially in children with obesity and cellular immunity.

Objectives: To compare antigen specific Interferon gamma+ T cell activation in obesity and healthy children at pre and post live attenuated HAV.

Methods: A retrospective pilot study, obtained blood samples of children and adolescents (212 participants) from previous study. Participants with either immunodeficiency or HAV immunization were excluded. Participants who met criteria; aged 8-12 years and BMI less than 1 SD or more than 2 SD, were included and divided into 2 groups; obese and healthy group. H2 strain, freeze dried, live attenuated HAV (MEVAC-A) were injected 0.5 ml in all participants. Blood for Interferon gamma+ T cell stimulation were collected at pre- and post-vaccination and measured via ELISPOT technique.

Results: 20 participants were included, mean age was 10.2 years. Overall Interferon gamma+ T cell activation demonstrated immunogenicity. However, there were no statistically significant difference of Interferon gamma+ T cell activation in both groups. Interferon gamma+ T cell stimulation GMR (95% CI) at concentration of 2,5,10 mcg/ml of HAV antigen at pre- and post-vaccination for healthy group were 0.66 (0.23-1.92), 1.18 (0.47-2.96), and 1.19 (0.55-2.57), and obese group were 1.06 (0.39-2.85), 1.15 (0.57-2.32), and 1.28 (0.76-2.18), respectively.

Conclusion: Single dose live attenuated HAV is safe and has high immunogenicity in children with obesity.