This is a prospective study analyzing the development of humoral immune response against SARS-Cov-2 in patients with previous Covid19: the aim is to compare the incidence, titration and evolution of IgG an IgM in a prospective cohort of liver transplant patients surviving to the first wave of Covid19, in comparison to not inmmunossupressed patients.

The liver transplant (HT) recipient population is more susceptible to infections than the general population. Few data are available regarding the incidence and clinical course of SARS-CoV-2 infection in this population, initially considered to be "high risk" regarding a possible higher incidence and severity of infection in these patients.

A prospective cohort of liver transplant recipient patients diagnosed with SARS-CoV-2 infection (Clinical Trials.gov Protocol Record HCB / 2020/0384) has been developed from SETH (Spanish Society for Liver Transplantation). This study aims to analyze the incidence and establish the clinical evolution of the infection in these patients. Initial data from the cohort, which includes 111 incidental cases diagnosed as of April 7, show a higher standardized incidence than the general population, but not higher mortality (data being published).

The chronic immunosuppression in t solid organ transplant patients could play a double role with respect to SARS-Cov-2 infection: on the one hand, it may condition a greater susceptibility and initial aggressiveness, in relation to itself viral effect, and in the other hand, it could protect by reducing the immune response that triggers the pulmonary and systemic inflammatory process.

After the initial Covid-19 outbreak, both in the general population and in immunosuppressed patients, the rate of specific IgM and IgG seroconversion against this coronavirus, and its protective capacity against reactivations or reinfections, are unknown. Therefore, it is a challenge for health organizations to identify the immune response in the population and to characterize its degree of protection, to adopt early measures to lessen the consequences of possible epidemic waves in the coming months.

Continuing with the prospective study of the cohort of liver transplant patients diagnosed with Covid-19 (SETH-Covid-19), already defined and composed of 91 living patients, the humoral immune response and its evolution in the first 12 months after initial infection. The cohort will incorporate the new incidental cases; A comparative study will be carried out with a contemporary cohort of non-immunosuppressed patients, controlled for age, gender and severity of the initial disease.

Inclusion Criteria:

Patients recovered of covid 19 Informed Consent

Exclusion Criteria:

Chemotherapy on going Concomitant Autoimmune diseases

Liver transplant and control patients (propensity score including age, sex, and severity of previous covid19 episode)

Multicenter study