Immunogenicity and safety of a third dose of anti-SARS-CoV-2 BNT16b2 vaccine in liver transplant recipients.

BACKGROUND & AIMS: A strategy to improve the low rate of anti-SARS-CoV-2 mRNA vaccine-induced immunogenicity in liver transplant recipients (LTs) is urgently needed. METHODS: We analyzed the rate of positive (≥0.8 U/ml) anti-SARS-CoV-2 receptor domain binding protein (RBD) antibody response two months after a third dose of the BNT16b2 vaccine in 107 LTs who completed the second vaccine dose seven months earlier. RESULTS: A positive anti-SARS-CoV-2-s-RBD antibody response after the third vaccine dose was detected in 98 (91.6%) LTs compared to 82 (76.6%) after the second vaccine dose (p=0.003). The median of anti-SARS-CoV-2 RBD antibody titers increased from 22.9 U/ml six months after the second to 3500 U/ml two months after the third vaccine dose (p<0.001). Fourteen (14.3%) responder patients presented antibody titers <100 U/ml, 57 (58.2%) between 100 and 9999 U/ml and 27 (27.6%) ≥10000 U/ml. Seropositivity after the second dose was maintained after the third dose. Independent predictors of antibody response failure after the third vaccine dose were taking a higher daily dose of mycophenolate mofetil (MMF, p<0.001) and had a lower (<60 ml/min/1.73m2 ) estimated glomerular filtration rate (p=0.007). Nine (9.1%) LTs experienced symptomatic SARS-CoV-2 infection after the third vaccine dose. Median antibody titers were not statistically different between infected and not infected LTs (1325 vs 3515 U/ml, p=0.678). CONCLUSIONS: The third dose of the BNT16b2 vaccine increased the number of LTs who developed a positive anti-SARS-CoV-2 s-RBD antibody response. A proportion of patients remained unresponsive, mainly for modifiable factors, such the use of MMF or multiple immunosuppressants.

Low risk of nosocomial severe acute respiratory syndrome-coronavirus-2 infection in patients with liver disease admitted to a hepatology unit at an academic hospital: A single-center experience.

BACKGROUND: Patients with liver disease may be at increased risk of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection due to immune dysfunction. However, the risk of nosocomial SARS-CoV-2 infection in these patients remains unknown. This study aimed to determine whether patients with liver disease are at an increased risk of nosocomial transmission of SARS-CoV-2 infection upon admission to the hospital for diagnostic or therapeutic procedures. METHODS: The study prospectively enrolled 143 patients who were admitted at least once to the hepatology unit at our hospital; 95 patients (66%) were admitted at least twice during the study period. History of past symptomatic SARS-CoV-2 exposure was assessed on the day before hospital admission via an interview. Patients were evaluated for active SARS-CoV-2 infection via real-time reverse transcription-polymerase chain reaction (RT-PCR) performed on nasopharyngeal swabs and tests for serum anti-SARS-CoV-2 immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies. RESULTS: None of the patients enrolled tested positive for SARS-CoV-2 infection by RT-PCR at the first or the second clinical evaluation. One patient who had previously received a liver transplant and who had a history of symptomatic SARS-CoV-2 infection that occurred 4 months before hospital admission tested positive for anti-SARS-CoV-2 IgG but not IgM antibodies at each of the two hospital admissions. CONCLUSIONS: The results of our study suggest that patients with liver disease are at no increased risk of nosocomial SARS-CoV-2 infection. These data support the policy of maintaining clinical hospital checks that will be necessary until or possibly even after the completion of the current SARS-CoV-2 vaccination campaign.

Past COVID-19 and immunosuppressive regimens affect the long-term response to anti-SARS-CoV-2 vaccination in liver transplant recipients.

BACKGROUND & AIMS: The long-term immunogenicity of anti-SARS-CoV-2 vaccines in liver transplant (LT) recipients is unknown. We aimed to assess the long-term antibody response of the Pfizer-BioNTech® BNT162b2 vaccine in LT recipients compared to controls. METHODS: LT recipients underwent anti-SARS-CoV-2 anti-receptor-binding domain protein IgG (anti-RBD) and anti-nucleocapsid protein IgG antibody (anti-N) measurements at the first and 1, 4 and 6 months after the second vaccination dose. RESULTS: One hundred forty-three LT recipients and 58 controls were enrolled. At baseline, 131/143 (91.6%) LT recipients tested anti-N negative (COVID-19 naïve), and 12/143 (8.4%) tested positive (COVID-19 recovered) compared to negative controls. Among COVID-19 naïve, 22.1% were anti-RBD positives 1 month after the first vaccine dose, while 66.4%, 77%, and 78.8% were 1, 4 and 6 months following the second vaccine dose. In contrast, 100% of controls were positive at 4 months (p <0.001). The median anti-RBD titer 4 months after the second vaccine dose was significantly lower (32 U/ml) in COVID-19 naïve than in controls (852 U/ml, p <0.0001). A higher daily dose of mycophenolate mofetil (MMF) (p <0.001), higher frequency of ascites (p = 0.012), and lower serum leukocyte count (p = 0.016) were independent predictors of anti-RBD negativity at 6 months. All COVID-19 recovered patients tested positive for anti-RBD at each time point. The median antibody titer was similar in those taking MMF (9,400 U/ml, 11,925 U/ml, 13,305 U/ml, and 10,095 U/ml) or not taking MMF (13,950 U/ml, 9,575 U/ml, 3,500 U/ml, 2,835 U/ml, p = NS) 3 weeks after the first and 1, 4 and 6 months after the second vaccine dose, respectively. CONCLUSIONS: In COVID-19-naïve LT recipients, the immunogenicity of anti-SARS-CoV-2 vaccination was significantly lower than that in controls. MMF was the main determinant of vaccination failure in SARS-CoV-2-naïve patients. LAY SUMMARY: The immunogenicity of anti-SARS-CoV-2 vaccination in liver transplant recipients is currently unknown. Herein, we show that liver transplant recipients who have not previously had COVID-19 are less likely to mount effective antibody responses to vaccination than a control population. The main determinant of vaccination failure was the use of the immunosuppressive drug mycophenolate mofetil.