Effectiveness of Bivalent mRNA COVID-19 Vaccines in Preventing COVID-19–Related Thromboembolic Events Among Medicare Enrollees Aged ≥65 Years and Those with End Stage Renal Disease — United States, September 2022–March 2023
Authors: Amanda B. Payne, Shannon Novosad, Ryan E. Wiegand, Morgan Najdowski, Danica J. Gomes, Megan Wallace, Jeffrey A. Kelman, Heng-Ming Sung, Yue Zhang, Bradley Lufkin, Yoganand Chillarige, Ruth Link-Gelles
Journal: MMWR Morbidity and Mortality Weekly Report (2024)

COVID-19 has been associated with an increased risk for thromboembolic events, including ischemic stroke, venous thromboembolism, and myocardial infarction.Studies have reported lower rates of COVID-19-related thromboembolic events among persons who received the COVID-19 vaccine compared with persons who did not, but rigorous estimates of vaccine effectiveness (VE) in preventing COVID-19-related thromboembolic events are lacking.This analysis estimated the incremental benefit of receipt of a bivalent mRNA COVID-19 vaccine after receiving an original monovalent COVID-19 vaccine.To estimate VE of a bivalent mRNA COVID-19 dose in preventing thromboembolic events compared with original monovalent COVID-19 vaccine doses only, two retrospective cohort studies were conducted among Medicare fee-for-service enrollees during September 4, 2022-March 4, 2023.Effectiveness of a bivalent COVID-19 vaccine dose against COVID-19-related thromboembolic events compared with that of original vaccine alone was 47% (95% CI = 45%-49%) among Medicare enrollees aged ≥65 years and 51% (95% CI = 39%-60%) among adults aged ≥18 years with end stage renal disease receiving dialysis.VE was similar among Medicare beneficiaries with immunocompromise: 46% (95% CI = 42%-49%) among adults aged ≥65 years and 45% (95% CI = 24%-60%) among those aged ≥18 years with end stage renal disease.To help prevent complications of COVID-19, including thromboembolic events, adults should stay up to date with COVID-19 vaccination.Original monovalent COVID-19 booster vaccine status Received*** 10,540, 003 (83.0) 5,089,503 (72.5) 5,450,500 (95.9) 0.68 61,680 (78.5) 40,733 (73.5) 20,947 (90.2) 0.44 Abbreviations: COPD = chronic obstructive pulmonary disease; ESRD = end stage renal disease; flu = influenza; HHS = U.S. Department of Health and Human Services; MS = musculoskeletal; NH = non-Hispanic; SMD = standardized mean or proportion difference.* Defined as having at least one dialysis encounter (excluding acute kidney injury) in the 90 days preceding the index date.Persons with ESRD receiving dialysis are eligible for Medicare benefits, regardless of age.† Beneficiaries had documented claims for ≥2 original monovalent mRNA vaccine doses, ≥2 Novavax vaccine doses, or ≥1 Janssen vaccine dose.A single dose (i.e., Janssen), second dose, third dose, or monovalent booster administration code was considered adequate to meet inclusion criteria.§ Defined as receipt of a bivalent mRNA COVID-19 vaccine dose at least 7 days earlier or receipt of original monovalent doses only.Bivalent doses were identified using codes from the Healthcare Common Procedure Coding System and Current Procedural Terminology and must have been administered after August 31, 2022.Beneficiaries' vaccination status could change during the study period.¶ A standardized mean difference of ≤0.1 indicates a negligible difference in means or proportions between groups.** https://www.atsdr.cdc.gov/placeandhealth/svi/index.html† † https://www.hhs.gov/about/agencies/iea/regional-offices/index.html§ § https://www.cdc.gov/nchs/data_access/urban_rural.htm#Use_of_the_Urban-Rural_Classification_with_Natality_and_Mortality_Files¶ ¶ Defined as ≥2 encounters with International Classification of Diseases, Tenth Revision, Clinical Modification code consistent with HIV diagnosis within 183 days before index date.*** Documentation of third dose or original monovalent vaccine booster administration code.Because there was documentation of receipt of original monovalent booster doses after the index date for some beneficiaries, this variable was considered time-varying.