A single-centre, observational study to evaluate immune response to Covid-19 vaccines in immunocompromised patients with haematological disorders (COVAC-IC)

ObjectiveTo evaluate immunological response to Covid-19 vaccines in immunocompromised haematology patients and compare with immunocompetent healthy controls DesignWe compared total Anti-SARS-CoV-2 spike antibody and T cell response in 45 immunocompromised haematology patients with 30 healthy adults following 2 doses of Covid-19 vaccine for 3 -5 months at 30 day intervals SettingSingle Centre, University Hospital, United Kingdom, March 2021-December 2021 Main Outcome measuresPeak quantitative total spike-specific antibody and cellular responses ResultsWe found O_LINon - significant difference in T cell and total Anti-SARS-CoV-2 S antibody response between study and control group patients C_LIO_LISix (13%) study group participants did not have detectable Total Anti-SARS -Cov-2 S antibodies at any time point throughout the study monitoring period. C_LIO_LIThree (7%) of the study group participants had no response, even after additional booster doses of Covid-19 vaccine. C_LIO_LIAll (100%) of the control group had detectable Anti-SARS-Cov-2 S antibodies after 2 doses of Covid-19 vaccine. C_LIO_LINo participant died or was hospitalised due to severe Covid-19 infection during the study period. This included study group participants who had no antibody response at any time point. C_LI ConclusionsThough there was a non - significant difference in T cell and total Anti-SARS-CoV-2 S antibody response between immunocompromised patients and healthy controls this did not result in any severe infection or Covid-19 related mortality in our study cohort. We did not identify any patient-specific factor (age, gender), specific haematological condition or treatment as determinant of response. Covid-19 vaccination was well tolerated without major side effects in both groups. What was already known about this topicprior to starting this study there were no studies to confirm immunological response following Covid-19 vaccination in immunocompromised haematology patients. During the conduct of our study there have been publications from researchers confirming blunted serological response in 62-66% of immunocompromised haematology patients compared to 74-95% in healthy controls. What this study addsOur study did not identify a significant difference in serological or T cell response between immunocompromised and healthy groups. Though 13% of immunocompromised patients had no response to Covid-19 vaccination none of them suffered from severe Covid-19 infection. We believe T cell response to Covid-19 vaccination has an important role in providing protective efficacy against Covid-19.