Currently the Pfizer-Biontech (mRNA), Sinovac (inactivated virus) and Astrazeneca-Oxford (adenovirus-vector) COVID-19 vaccines are available for vaccination in HK. The American Association of Liver Disease has recently published consensus statements for COVID-19 vaccination in subjects with chronic liver disease (CLD). Patients with CLD have dysregulated innate and adaptive immune response that may be associated with vaccine hypo-responsiveness and there are no data as to whether these patients may respond differently to the various vaccines. The Humanity and Health Medical Center (HHMC) is an active participant of the HK government COVID-19 vaccination programs and patients with CLD follow-up at HHMC will have access to the three different vaccines. The aim of this prospective study is to compare the antibody response of CLD subjects to the Pfizer-Biontech (mRNA), Sinovac (inactivated virus) and Astrazeneca-Oxford (adenovirus-vector) COVID-19 vaccines.

Inclusion Criteria:

1. Subjects with chronic liver disease (CLD) at the Humanity and Health Medical Group and eligible for the HK government vaccination programme;
2. Able to understand and sign informed consent.;
3. Underlying CLD- defined as patients with chronic hepatitis B or C infections, liver cirrhosis, metabolic associated liver disease, hepatocellular carcinoma, alcoholic liver disease, autoimmune hepatitis, hemochrombtosis.

Exclusion Criteria:

1. Patients contraindicated for the COVID -19 Vaccination Program due to uncontrolled co-morbitities;
2. Past allergies to other vaccines;
3. Pregnant subjects.