Three Doses of Moderna mRNA COVID-19 Vaccine Augmented Responses Among Solid Organ Transplant Recipients

Although phase 3 trials of COVID-19 vaccines excluded solid organ transplant (SOT) recipients, several cohort studies have demonstrated that serologic responses to COVID-19 vaccines are much lower in SOT recipients than immunocompetent persons (NEJM JW Infect Dis Jul 2021; multiple citations). Now, researchers in Canada report the first randomized trial of a third dose of mRNA-1273 (Moderna) COVID-19 vaccine in 120 SOT recipients (mean age, 66.6; median time since transplant, 3.2 years). Participants received placebo or a third dose of vaccine 2 months after the second dose. More than 80% were receiving either mycophenolate or azathioprine (both associated with hypo-responsiveness to vaccines).

Anti–receptor-binding domain (RBD) antibody lev…