Effect of Immune Cell Ageing on Humoral Immunity Responses Post-COVID-19 Vaccination

Background: COVID-19 pandemic has high incidence and mortality, including in Indonesia. One of the prevention efforts is the provision of vaccines, but the ageing of the immune system (immunosenescence) may reduce the immune response to vaccination. Studies reported the decline of interferon-gamma (IFN-γ) could be one of markers of immune cell ageing. Besides, the increases soluble CD28 (sCD28) reported has good correlation with membrane CD28 (mCD28), thus it could be used as an alternative marker for immunosenescence. Objective: To determine the differences in levels of sCD28, IFN-γ and anti-S-RBD antibodies in the group suspected of having an ageing immune system with the control group after vaccination. Methods: Sample consisted of 24 control (healthy adult) and 32 case (elderly and adult with comorbid) subjects. Blood samples were examined for anti-S-RBD antibody, IFN-γ, and sCD28 levels. Analysis of data performed by Median test and Spearman tests. Results: Mean level of anti-S-RBD antibodies, IFN-γ, and sCD28 in case group compared to control group was 33.0 ±17.47 BAU/mL vs. 45.97 ± 23.13 BAU/mL (p = 0.007); 41.61 ± 38.79 ng/mL vs. 98.59 ± 94.31 ng/mL (p = 0.007); and 3.80 ± 3.68 ng/mL vs. 7.81 ± 7.97 ng/mL (p = 0.280), respectively. The anti-S-RBD antibodies and IFN-γ levels are lower in case group and sCD28 is lower in case group although not statistically significant. Conclusion: Anti-S-RBD antibodies after COVID-19 vaccination are lower in elderly or comorbid people than in adults without comorbid because of ageing of immune system.