Table 1.

COVID-19 vaccine response in patients receiving B-cell depletion with rituximab.

Author	PMID	Vasculitis (n, % total cohort)	Detection kit	Vaccine	%, positivity (vasculitis)	Important findings
Seyahi	34109466	7 (6.9%)	Elecsys®	CoronaVac	71.4%	All patients with vasculitis were in the low (<117 U/mL) titre group; all 7 rituximab users were in the low titre group.
Spiera	33975857	17 (19.1%)	Elecsys®, Atellica®	BNT162b2, mRNA-1273	52.9%	20/30 rituximab users without serologic response Median time from last infusion to first vaccination was 98 days in antibody-negative patients, 704.5 days in those with positive serology. The percentage of circulating B-cells was 0% and 4% in antibody non-responders vs. responders.
Furer	34127481 (ref. 66)	26 (3.8%)	Liaison®	BNT162b2	30.8%	The time interval between last administration of rituximab and BNT162b2 administration had a significant impact on immunogenicity.
Connolly CM	34029488	3 (15%)	Elecsys®	BNT162b2, mRNA-1273	0%⁎	55% of the cohort received rituximab; 50% received mycophenolate mofetil (2 patients with neither rituximab nor mycophenolate mofetil). Median timing of rituximab before dose 1 was 14 weeks.
Connolly CM	Accepted (ref. 65)	48 (100%)	Elecsys®, Liaison®	BNT162b2, mRNA-1273,	37.5%	None of the patients receiving their COVID-19 vaccine within 4 months of rituximab administration had detectable antibodies. 3/22 who received rituximab 6 months before COVID-19 vaccination had antibodies. Median CD19+ B-cell count 4 versus 0 (responders versus non-responders). More patients receiving mRNA-1273 had an antibody response.

^⁎The study by Connolly CM, et al. focused on patients with rheumatic diseases and absence of antibody response following two doses of mRNA vaccines.