PT - JOURNAL ARTICLE AU - Yau, Kevin AU - Chan, Christopher T. AU - Abe, Kento T. AU - Jiang, Yidi AU - Atiquzzaman, Mohammad AU - Mullin, Sarah I. AU - Shadowitz, Ellen AU - Liu, Lisa AU - Kostadinovic, Ema AU - Sukovic, Tatjana AU - Gonzalez, Anny AU - McGrath-Chong, Margaret E. AU - Oliver, Matthew J. AU - Perl, Jeffrey AU - Leis, Jerome A. AU - Bolotin, Shelly AU - Tran, Vanessa AU - Levin, Adeera AU - Blake, Peter G. AU - Colwill, Karen AU - Gingras, Anne-Claude AU - Hladunewich, Michelle A. TI - Differences in mRNA-1273 (Moderna) and BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 vaccine immunogenicity among patients undergoing dialysis AID - 10.1503/cmaj.211881 DP - 2022 Feb 28 TA - Canadian Medical Association Journal PG - E297--E305 VI - 194 IP - 8 4099 - http://www.cmaj.ca/content/194/8/E297.short 4100 - http://www.cmaj.ca/content/194/8/E297.full SO - CMAJ2022 Feb 28; 194 AB - Background: Differences in immunogenicity between mRNA SARS-CoV-2 vaccines have not been well characterized in patients undergoing dialysis. We compared the serologic response in patients undergoing maintenance hemodialysis after vaccination against SARS-CoV-2 with BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna).Methods: We conducted a prospective observational cohort study at 2 academic centres in Toronto, Canada, from Feb. 2, 2021, to July 20, 2021, which included 129 and 95 patients who received the BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines, respectively. We measured SARS-CoV-2 immunoglobulin G antibodies to the spike protein (anti-spike), receptor binding domain (anti-RBD) and nucleocapsid protein (anti-NP) at 6–7 and 12 weeks after the second dose of vaccine and compared those levels with the median convalescent serum antibody levels from 211 controls who were previously infected with SARS-CoV-2.Results: At 6–7 weeks after 2-dose vaccination, we found that 51 of 70 patients (73%) who received BNT162b2 and 83 of 87 (95%) who received mRNA-1273 attained convalescent levels of anti-spike antibody (p < 0.001). In those who received BNT162b2, 35 of 70 (50%) reached the convalescent level for anti-RBD compared with 69 of 87 (79%) who received mRNA-1273 (p < 0.001). At 12 weeks after the second dose, anti-spike and anti-RBD levels were significantly lower in patients who received BNT162b2 than in those who received mRNA-1273. For anti-spike, 70 of 122 patients (57.4%) who received BNT162b2 maintained the convalescent level versus 68 of 71 (96%) of those who received mRNA-1273 (p < 0.001). For anti-RBD, 47 of 122 patients (38.5%) who received BNT162b2 maintained the anti-RBD convalescent level versus 45 of 71 (63%) of those who received mRNA-1273 (p = 0.002).Interpretation: In patients undergoing hemodialysis, mRNA-1273 elicited a stronger humoral response than BNT162b2. Given the rapid decline in immunogenicity at 12 weeks in patients who received BNT162b2, a third dose is recommended in patients undergoing dialysis as a primary series, similar to recommendations for other vulnerable populations.