Immunogenicity of a Third Dose of BNT162b2 Vaccine among Lung Transplant Recipients-A Prospective Cohort Study

Abstract

Two doses of mRNA SARS-CoV-2 vaccines elicit an attenuated humoral immune response among immunocompromised patients. Our study aimed to assess the immunogenicity of a third dose of the BNT162b2 vaccine among lung transplant recipients (LTRs). We prospectively evaluated the humoral response by measuring anti-spike SARS-CoV-2 and neutralizing antibodies in 139 vaccinated LTRs ~4-6 weeks following the third vaccine dose. The t-cell response was evaluated by IFNγ assay. The primary outcome was the seropositivity rate following the third vaccine dose. Secondary outcomes included: positive neutralizing antibody and cellular immune response rate, adverse events, and COVID-19 infections. Results were compared to a control group of 41 healthcare workers. Among LTRs, 42.4% had a seropositive antibody titer, and 17.2% had a positive t-cell response. Seropositivity was associated with younger age (t = 3.736, p < 0.001), higher GFR (t = 2.355, p = 0.011), and longer duration from transplantation (t = -1.992, p = 0.024). Antibody titer positively correlated with neutralizing antibodies (r = 0.955, p < 0.001). The current study may suggest the enhancement of immunogenicity by using booster doses. Since monoclonal antibodies have limited effectiveness against prevalent sub-variants and LTRs are prone to severe COVID-19 morbidity, vaccination remains crucial for this vulnerable population.

Keywords: BNT162b2 COVID-19 vaccine; immunogenicity; lung transplantation; third dose.

Figure 1

Seropositivity among LTRs and control group before and after the third vaccine dose. A column scatter plot graph representing the BNT162b2 vaccine-induced S1-IgG antibody levels (AU/mL) in lung transplant recipients and control group before and after the third vaccine dose. The bars represent median values. Abbreviations: LTRs, lung transplant recipients; AU, antibody units; Neg, LTRs with seronegative antibody titer: Pos, LTRs with seropositive antibody titer; C, control group antibody titer.

Figure 2

Neutralizing antibodies and seropositive s-IgG titer Correlation. A Pearson correlation plot representing the correlation between S1-IgG antibody levels (AU/mL) and neutralizing antibody titer among vaccinated lung transplant recipients. The small upper Pearson correlation plot represents a magnified view with a scale of 5000 Total Abs (AU/mL). Abs, antibodies; AU, antibody units.