BOOST KIDNEY: A Randomized Controlled Trial of Third Dose BNT162b2 vs. mRNA-1273 COVID-19 Vaccination in CKD and Dialysis Patients

ABSTRACT

Background: Due to waning humoral immunity, a third COVID-19 vaccine dose is recommended but there is a lack of evidence regarding whether there is benefit to homologous versus heterologous mRNA vaccination. Method(s) This was a multi-centre parallel group randomized controlled trial in Toronto, Ontario from September 30, 2021 to May 13, 2022 which enrolled participants with stage 3B-5 chronic kidney disease with prior homologous mRNA two dose vaccination. Overall 273 participants were randomized 11 to either 30mug BNT162b2 (n=137) or 100 mug mRNA-1273 (n=136) third dose stratified by initial vaccine type. Neutralizing antibodies against the B.1.1.529 (Omicron) variant of concern as well as binding SARS-CoV-2 IgG antibodies to the spike protein, receptor binding domain, and nucleocapsid protein were measured. Result(s) Participants had a median age of 67 years, 94% were on dialysis, 3% had prior COVID-19, and 59% had received BNT162b2 for initial two dose vaccination. Prior to the third vaccine dose, detectable Omicron neutralizing antibodies were present in 2% with BNT162b2 and 54% with mRNA-1273 two dose vaccination. At 1 month post third dose, among those with baseline BNT162b2, Omicron-specific neutralizing antibodies were detectable in 84% with third dose BNT162b2 in comparison to 83% with third dose mRNA-1273 (p=0.70). In those with baseline mRNA-1273, 100% receiving third dose mRNA-1273 had Omicron-specific neutralizing antibodies in comparison to 96% with third dose BNT162b2 (p=0.75). During the study period, 9.3% of participants (n=25) contracted COVID-19 and two died from COVID-19 with no difference in infection based on vaccine type (p=0.26). Conclusion(s) In this randomized controlled trial of third dose COVID-19 vaccination, both homologous and heterologous vaccination elicited robust SARS-CoV-2 neutralizing antibody response. (Figure Presented).