September 15, 2022 COBALT completes patient recruitment The COBALT study will provide evidence of the protective effect of coronavirus disease (COVID-19) vaccination in patients with chronic liver disease and help issue recommendations for future vaccination programs.

BARCELONA—Recruitment of 1159 patients ended in September. Sponsored by the European Foundation for the Study of Chronic Liver Failure (EF CLIF), the COBALT study – COVID-19 vaccination and biomarkers in cirrhosis and post-liver transplantation – will compare responses after dose 2 and dose 3 of the COVID-19 vaccine in patients with cirrhosis, following liver transplantation or autoimmune liver disease, with healthy subjects as a control group. The level of antibody response, the durability of the response and degree of protection against COVID-19 will be also assessed.

As of 12 May 2020, there are 283,153 deaths for COVID-19 worldwide according to the World Health Organization (WHO). Patients with cirrhosis, acute-on-chronic liver failure (ACLF), and hepatocellular carcinoma appear to be at high risk of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and progress to most severe forms of COVID-19 with at least 5-fold increased risk of death.

Vaccination against SARS-CoV-2 has been proven effective to reduce hospitalization and death from COVID-19 in individuals without immunosuppression, but existing data demonstrate that a markedly reduced fraction of transplant recipients are able to mount positive antibody responses after 1 or 2 doses of SARS-CoV-2 messenger RNA (mRNA) vaccine. There are relatively few data demonstrating the effectiveness of these vaccines in preventing breakthrough infections in liver transplant recipients. Moreover, there are few data to measuring the antibody response, or degree of protection from vaccination, in patients with cirrhosis.

More scientific evidence to guide effective clinical management and vaccination strategies for patients with chronic liver disease

In order to fill this knowledge gap, EF CLIF in collaboration with the Foundation for Liver Research, European Association for the Study of the Liver (EASL), European Liver and Intestine Transplant Association (ELITA) and European Patients’ Association (ELPA) joined efforts to assess the degree of protection against COVID-19 after the primary vaccination schedule and subsequent booster in patients with cirrhosis, autoimmune liver disease and post-liver transplantation.

As this is a prospective observational study, the research team recruits participants over time. In all three groups, demographic data, medical history, comorbidities and medications will be collected and blood samples for laboratory analyses processed.

The research team is also studying children aged 12–16 with liver disease or liver transplantation, for their responses to COVID-19 vaccination. These data are of particuarvalue, since very few studies have been conducted in pediatric patients.

Gautam Mehta, Principal Investigator for COBALT and based at University College London, UK, explained that the results from the COBALT study “will provide valuable insight into factors predicting vaccine response and new infection in these vulnerable patients. In particular, we want to know if the vaccines protect against the newer variants, such as Omicron. We believe the data will impact how booster vaccines are used in the future for liver patients”.

This study is supported by the European Foundation for the Study of Chronic Liver Failure.


The aim of the COBALT study is to determine the protective effect of COVID-19 vaccination in liver disease. Patients with cirrhosis have been shown to have markedly worse outcomes from COVID-19. Moreover, there is very little data on the effectiveness of SARS-CoV-2 vaccines in cirrhosis or liver transplant patients since they were not included in initial clinical trials. We will compare responses after dose 2 and dose 3 of the vaccine with healthy controls, to look at the level of antibody response. We will also investigate the durability of response and degree of protection against breakthrough SARS-CoV-2 infection.


The European Foundation for the Study of Chronic Liver Failure (EF CLIF) is a private non-profit organization connecting biomedical researchers and healthcare professionals with each other, with patients and patient associations, and with society. The fundamental purpose of EF CLIF, reflected in its founding Statements of 2015, is to advance knowledge and promote research and education in liver disease to improve the prognosis of patients living with chronic liver failure.

The Foundation has made pioneering efforts in conducting a series of large, international prospective studies that have been instrumental in reclassifying the trajectory of patients with chronic liver failure and led to the clinical, prognostic and pathophysiological definition of the syndrome referred to as “acute-on-chronic liver failure” characterized by acute decompensation of cirrhosis, severe systemic inflammation, organ failures, and high short-term mortality. We are inspiring best clinical practices for the management of patients with chronic liver failure and promoting a more sustainable and equitable healthcare system.

Within the Foundation, the European Association for the Study of the Liver (EASL) Chair supports research activities through the EASL-CLIF Consortium, a network of 117 tertiary care and university hospitals in 28 European countries. The Grifols Chair promotes translational studies in centers across Europe and North America within the framework of the European Network for Translational Research (ENTR) with 25 centers in 8 countries. Over the last five years, the Foundation has successfully expanded its geographical scope providing the context to support transcontinental collaborative research projects. The Global Projects chapter provides the framework to promote research in cirrhosis across the world with the aim to help to build consensus and ensure health equity worldwide.