SARS­CoV­2 vaccination in liver transplant recipients: factors affecting immune response and refusal to vaccine.

INTRODUCTION: The effectiveness of SARS­CoV­2 vaccination in liver transplant (LT) recipients varies between reports. OBJECTIVES: In this study, we analyzed the immune response to the SARS­CoV­2 vaccine, factors affecting the response, and reasons for the vaccine refusal. PATIENTS AND METHODS: Among 300 consecutive LT recipients, 75% were vaccinated. The humoralresponse was assessed by the quantitative determination of antitrimeric spike protein­specific IgG antibodies to SARS­CoV­2. Thirty­four vaccinated patients with prior SARS­CoV­2 infection were analyzed separately. RESULTS: Among 192 LT recipients vaccinated without past natural infection, 69% developed the immune response (median time of 125 days after the second dose). Older age, worse kidney function, and dual immunosuppression negatively affected the humoral response. Mycophenolate mofetil increased the risk of nonresponse (odds ratio [OR], 2.99; 95% CI, 1.45-6.19). The antibody concentration was higher in the first 90 days from the second dose and stable as compared with 90-150 days and over 150 days. LT recipients with prior COVID­19 presented with a robust immune response (100%). The female sex, living in a rural area, lower body mass index, and younger age (all P <0.05) were associated with the refusal of the vaccine. CONCLUSIONS: The lower immune response in the vaccinated LT recipients than in the general population justifies administering the third dose of the vaccine. However, more data are needed to recommend any therapy modification before the vaccination.

COVID-19: Focus on the lungs but do not forget the gastrointestinal tract.

The coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 was declared in the last weeks as global pandemic. Currently affecting more than 5 000 000 individuals worldwide, COVID-19 is most commonly associated with symptoms caused by the acute respiratory distress syndrome (ARDS). As the number of infected individuals increases, we are learning that not only lungs, but also other organs can be affected by the virus. The gastrointestinal symptoms, for example diarrhoea, vomiting, nausea or abdominal pain, are frequent in patients with COVID-19. Moreover, alimentary tract symptoms may precede the respiratory presentation of SARS-CoV-2 infection. This can lead to delayed diagnosis and inappropriate management of infected patients. In addition, SARS-CoV-2 nucleic acid can be detected in faeces of infected patients and rectal swabs are even reported to remain positive for a longer period of time than nasopharyngeal swabs. Here, we aim to provide an update on the gastrointestinal involvement of COVID-19 presenting the symptoms that can be encountered in infected patients. We address the role of angiotensin-converting enzyme 2 (ACE2), as a functional receptor for SARS-CoV-2, which also was found in the gastrointestinal tract. Finally, we briefly discuss faecal shedding of SARS-CoV-2 and its potential role in the pathogenesis of the disease.