Humoral and T-cell mediated response after administration of mRNA vaccine BNT162b2 in frail populations

Abstract

Patients with frailty are considered to be at greater risk to get severe infection from SARS-CoV-2. One of the most effective strategies is vaccination. In our study we evaluated both the humoral immune response elicited by the vaccination at different time points, and the T-cell response in terms of interferon (IFN)-γ production in frail patients and healthy donors. Fifty-seven patients (31 patients undergoing hemodialysis and 26 HIV positive subjects) and 39 healthcare workers were enrolled. All participants received two doses of the mRNA vaccine BNT162b2. Healthcare workers showed a significantly higher antibody titer than patients twenty-one days after the first dose (p < 0.001). From the same time point we observed for both groups a decay of the antibody levels with a steeper slope of decline in the patients group. Regarding T-cell response the only significant difference between non-reactive and reactive subjects was found in median antibody levels, higher in the responders group than in non-responders. The healthcare workers seem to better respond to the vaccination in terms of antibodies production; the lack of T-cell response in about 50% of the participants seems to suggest that in our study population both humoral and cell-mediated response decline over time remarking the importance of the booster doses, particularly for frail patients.

Keywords: HIV; Hemodialysis; Humoral response; SARS-CoV-2; T-cell response; Vaccine.

Fig. 1

Box plot of IgG levels 21 days after first dose in healthcare workers and HIV/Dialysis Patients, showing medians, interquartile ranges and outliers.

Fig. 2

Trend of median IgG levels at 7, 14, 21, 90 and 270 day after the second vaccine dose for healthcare workers (blue line) and HIV/Hemodialysis patients (orange line). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Box plot of IgG levels before the third vaccine dose in Non-Reactive (subjects in which no effector T-cell-mediated response was detected) and Reactive (subjects in which an effector T-cell-mediated response was detected) subjects, showing medians, interquartile ranges and outliers.