Original Clinical Science
Third dose of the BNT162b2 vaccine in heart transplant recipients: Immunogenicity and clinical experience

https://doi.org/10.1016/j.healun.2021.08.010Get rights and content

BACKGROUND

The repeated waves of the COVID-19 pandemic have highlighted the necessity to optimize vaccine responses in immunocompromised populations. We investigated the safety and immunogenicity of a third, booster, dose of the Pfizer BNT162b2 vaccine in heart transplant (HT) patients.

METHODS

The cohort comprised 96 adult HT patients who received a third homologous dose of the BNT162b2 vaccine 168 days after the second dose. The vaccine-induced antibody responses of both receptor-binding domain (RBD) IgG and neutralizing antibodies were assessed in all patients, with a positive antibody response being defined as the presence of either IgG anti-RBD or neutralizing antibodies. For a subset of patients, T cell response was also studied.

RESULTS

The third dose was associated with a low rate of adverse events, mostly mild pain at the injection site. No serious adverse events were recorded, and there were no episodes of rejection. At 18 days following the third dose of the vaccine, the positive antibody response increased from 23% to 67%, with a corresponding increase in neutralizing capacity. The third dose elicited SARS-CoV-2 neutralization titers >9-fold and IgG anti-RBD antibodies >3-fold of the range achieved after the two primary doses. Mycophenolate use, lower eGFR and higher C-reactive protein were independently associated with a reduced likelihood of generating an immune response. Importantly, a specific T-cell response following the third dose was evident in the majority of transplant recipients.

CONCLUSIONS

An homologous third booster dose of the BNT162b2 vaccine gave overall consistent tolerability and a good safety profile, while eliciting humoral and cellular immune responses.

KEYWORDS

heart transplantation
COVID-19 pandemic
booster
BNT162b2 vaccine
IgG anti-RBD
neutralizing antibodies

Abbreviations

COVID-19
coronavirus disease 2019
CRP
C-reactive protein
eGFR
estimated glomerular filtration rate
ELISA
enzyme-linked immunosorbent assay
GMT
geometric mean titer
HT
heart transplantation
IFN-γ
interferon gamma
ISHLT
International Society for Heart and Lung Transplantation
PBMCs
peripheral blood mononuclear,r cells
RBD
receptor-binding domain
SARS-CoV-2
severe acute respiratory syndrome coronavirus-2
SOT
solid organ transplants

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1

These authors contributed equally to this work

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