Focus	Research-related issues	Considerations
Measurement of humoral and cellular immunity	Measurement of antibody levels at various time-points. How do various agents impair vaccine response?	Measure antibodies 2–4 weeks after completion of the vaccination, measure cellular response (if feasible) at the same time-point. In positive patients, measure antibodies during routine clinical follow-up (first assessment after 3 months or during routine controls?) Attributes of different immunosuppressive measures: rituximab, cyclophosphamide, azathioprine, mycophenolate mofetil, high-doses of steroids.
Efficacy outcome	Assessment of efficacy of different vaccine platforms to prevent mild/moderate COVID-19 and especially severe/life-threatening SARS-CoV-2 infections.	Is a cellular immune response sufficient to prevent severe disease (especially in rituximab-treated patients)? Consider booster doses early after vaccination.
Vaccination after SARS-CoV-2 infection	What is the risk of re-infection of patients following COVID-19? When is the ideal timepoint to vaccinate patients?	Define the vaccine response in patients with pre-existing antibodies; is one dose of the respective vaccine sufficient to mount an adequate immune response or do patients need a second dose.
Use of different vaccines (if unresponsive)	What strategy should we use in patients who fail to mount an adequate immune response?	Administration of additional doses of the same or different vaccines (“heterologous vaccination strategy”) or different routes of administration (e.g. a respiratory booster dose, if approved) may be considered.
Safety	Systematic assessment of systemic/local reactions. Impact of COVID-19 vaccines on relapse risk/risk to develop de novo disease.