Immunosuppression and Covid-19: Risk factor or treatment?

ABSTRACT

Introduction: During the Covid-19 pandemic, 540,895 people were identified as immunosuppressed and believed to be at increased risk of severe disease.1 As the pandemic evolved, biologic immunosuppression became a treatment of severe Covid-19.2 The true impact of immunosuppression on disease severity remains unclear. Objective(s) 1. Identify the incidence of immunosuppressed patients admitted to the ICU. 2. Analyse the mortality of those who are immunocompetent and immunosuppressed. 3. Examine the differences in mortality and level of care required between sub groups of patients on immunosuppression;those on biologics, non-biologics, and a combination of both. Method(s) A retrospective search of all Covid-19 positive admissions from March 2020 to November 2021 across two adult ICUs at Chelsea & Westminster NHS Trust was performed, using the EPR system. We identified those on immunosuppressive drugs, the level of care they required, and 28 day mortality. We categorised different types of immunosuppression, vaccination status, if applicable and co-morbidities. The exclusion criteria were primarily those with false positive swabs or incomplete data. Result(s) Baseline characteristics were median age (56 vs 56), and APCHE II score (20.08 in the immunosuppressed group vs 14.0 in immunocompetent). Thirteen immunosuppressed patients were identified. Reasons for drug immunosuppression in this group included solid organ transplant (6/13), and autoimmune conditions (7/13). Two patients were on biologic drugs alone, 8 were on non-biologics, and 3 were on a combination. Four of this group had received at least 2 doses of a Covid-19 vaccine. Mortality was 61.54% (8/13) in the immunosuppressed group vs 36.65% (199/543) in the immunocompetent group. Conclusion(s) Despite similar demographics, patients on immunosuppression had a significantly higher mortality than the immunocompetent group. Interestingly, those on targeted biological immunosuppression had the lowest incidence of requiring level 3 care, and no deaths. It is a possibility that biologics dampen the hyper-inflammation seen in severe Covid-19 pneumonitis, raising the question of a possible protective benefit from severe disease. This reflects the findings of the REMAP-CAP investigators,3 who showed that the IL-6 inhibiting biologics Tocilizumab and Sarilumab are efficacious against the most severe disease following admission to ICU with Covid-19 pneumonitis. The single centre and retrospective observational design, combined with small numbers on immunosuppression, despite a large inclusion criterion, mean it is not possible to make statistical conclusions. Confounding factors include the effects of vaccination, shielding and the change in SARS-CoV-2 variant prevalent during different times during the pandemic.