COvid-19 Vaccine Booster in Immunocompromised Rheumatic Diseases

Systemic autoimmune rheumatic diseases (SARDs) include rheumatoid arthritis (RA), systemic lupus (SLE), systemic vasculitis, and related diseases where immune system activity causes widespread inflammation in organs, leading to sickness, organ damage, disability, high health costs, and even death. With no cure, SARDs require life-long immunosuppression. People living with SARDs now face a new and urgent dilemma: immunosuppression increases risk for worse COVID-19 infection, yet an immune stimulation, such as vaccination, could re-activate their disease. Fear of vaccine-related disease reactivation is not of concern in other immunosuppressed groups (e.g. patients receiving chemotherapy or hemodialysis) but in SARDs, disease flare could lead to organ failure or even death. Specific research in this population is therefore critical. Moreover, among SARD patients, those on anti-CD-20 monoclonal antibody (mAb) (i.e. rituximab (anti-CD-20 mAb)) have extremely low humoral immunity post-COVID-19 mRNA vaccine. As of mid-July 2021, 1489 SARDs patients were actively treated with anti-CD-20 mAb in the province of Quebec (personal communication).

This study will test the hypothesis that a booster dose of a COVID-19 vaccine is safe and enhances post-vaccine humoral and cellular responses in SARDs patients on anti-CD-20 mAb treatment. The magnitude of this response depends on the type of COVID-19 vaccine administered and is optimal when the booster dose is a vaccine from a different group than the one used for primary immunization (mix-and-match approach).

Our goal is to recruit 287 adults with SARDs on anti-CD-20 mAb treatment post-three doses of an approved mRNA-COVID-19 vaccine in a non-randomized, open label, comparative clinical trial with pragmatic features. This includes persons with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), inflammatory immune myopathies (IIM), overlap and undifferentiated connective tissue diseases (OCTD and UCTD) and ANCA-associated vasculitis (AAV). We will test at entry all participants for their anti-SARS-CoV-2-spike receptor binding domain (anti-RBD) antibody response to their previous doses of mRNA-COVID-19 vaccines. For participants who have received 3 doses of an mRNA vaccine, we will offer them a choice between a fourth dose of an mRNA (vaccine and a dose of a protein subunit vaccine (PSV). For participants who have already received 4 doses of an mRNA vaccine in the community, they will be offered a dose of a protein subunit vaccine (PSV) as a fifth dose.

The primary study outcome will be the assessment of the safety and reactogenicity of a booster dose of COVID-19 vaccine using a mix-and-match strategy in immunocompromised rheumatic disease patients on an anti-CD-20 mAb. The secondary study outcome will be the humoral responses as measured by the anti-RBD Ab 28 days post vaccination. Exploratory outcomes include the cellular response at 28 days; the delayed humoral responses at 6 months; a comparison of the immunogenicity between types of vaccine (mRNA vs PSV); the evaluation of the effects of concomitant treatments on immunogenicity post-COVID-19 vaccine; the description of the rates of disease flares post booster dose of COVID-19 vaccine; and a description of the decision process for vaccine selection.