RESUMO
INTRODUCTION AND OBJECTIVES: Lower antibody (Ab) responses after SARS-CoV-2 vaccination have been reported in liver transplant (LT) recipients and those with chronic liver diseases (CLD). The role of a booster dose in those with poor responses to initial vaccination is not well defined. METHODS: In this prospective study, we determined antibody (Ab) response to spike protein after a booster dose in LT recipients and those with chronic liver diseases (CLD) with and without cirrhosis after they had a poor response to an initial standard regimen. RESULTS: Of the 80 patients enrolled, 45 had LT, and 35 had CLD (18 with cirrhosis). A booster dose was given at a median of 138.5 days after the completion of the standard regimen. After the booster dose, 58 (73%, 31 LT, 27 CLD) had good response (≥250 U/mL), and 22 (28%, 14 LT, and 8 CLD) had poor response (7 undetectable and 15 with low Ab levels). No patient had any serious adverse events. The antibody responses were lower in those who had undetectable Ab (80 U/mL) than those who had low levels of Ab (0.80-249 U/mL) after the standard vaccination regimen (42% vs. 87%, p=0.0001). The antibody responses after homologous and heterologous booster doses were similar. CONCLUSIONS: We have shown that a booster dose will enhance Ab responses in LT recipients and those with CLD who had poor responses after an initial vaccine regimen.