Real-World Effectiveness of a Third Dose of mRNA-1273 Versus BNT162b2 on Inpatient and Medically Attended COVID-19 Among Immunocompromised US Adults.

ABSTRACT

INTRODUCTION: Recent data have shown elevated infection rates in several subpopulations at risk of SARS-CoV-2 infection and COVID-19, including immunocompromised (IC) individuals. Previous research suggests that IC persons have reduced risks of hospitalization and medically attended COVID-19 with two doses of mRNA-1273 (SpikeVax; Moderna) compared to two doses of BNT162b2 (Comirnaty; Pfizer/BioNTech). The main objective of this retrospective cohort study was to compare real-world effectiveness of third doses of mRNA-1273 versus BNT162b2 at multiple time points on occurrence of COVID-19 hospitalization and medically attended COVID-19 among IC adults in the United States (US). METHODS: This retrospective, observational comparative effectiveness study identified patients from the US HealthVerity database from December 11, 2020, through August 31, 2022. Medically attended SARS-CoV-2 infections and hospitalizations were assessed following a three-dose mRNA-1273 versus BNT162b2 regimen. Inverse probability weighting was applied to balance baseline confounders between vaccine groups. Relative risk (RR) and risk difference were calculated for subgroup and sensitivity analyses using a non-parametric method. RESULTS: In propensity score-adjusted analyses, receiving mRNA-1273 vs. BNT162b2 as third dose was associated with 32.4% (relative risk 0.676; 95% confidence interval 0.506-0.887), 29.3% (0.707; 0.573-0.858), and 23.4% (0.766; 0.626-0.927) lower risk of COVID-19 hospitalization after 90, 180, and 270 days, respectively. Corresponding reductions in medically attended COVID-19 were 8.4% (0.916; 0.860-0.976), 6.4% (0.936; 0.895-0.978), and 2.4% (0.976; 0.935-1.017), respectively. CONCLUSIONS: Our findings suggest a third dose of mRNA-1273 is more effective than a third dose of BNT162b2 in preventing COVID-19 hospitalization and breakthrough medically attended COVID-19 among IC adults in the US.