COVID-19 Vaccine Lowers Venous Thromboembolism, Mortality Risk

Patients vaccinated against COVID-19 reported a 59% lower risk of both venous thromboembolism (VTE) and death within 30 days of infection, according to a study in Research and Practice in Thrombosis and Haemostasis.¹

“Among hospitalized patients, COVID-19 carries a greater risk of VTE events than does influenza,” according to TCTMD.² “Compared with patients hospitalized with flu during the 2018-2019 season, those who landed in the hospital with COVID-19 were more likely to develop deep vein thrombosis or pulmonary embolism within 90 days, both before and after vaccines against SARS-CoV-2 were available.”

Building on these observational findings, national research from the National Clinical Cohort Collaborative database demonstrates that the elevated risk of blood clots and mortality was most acute during the early Ancestral and Delta variant waves of COVID-19. However, during the contemporary Omicron era, its clinical risk profile converged with that of non-COVID acute respiratory infections.¹

READ MORE: COVID-19, Flu Shots Coadministered Are Well-Tolerated in Pregnancy

Evolutionary Trends in Virulence and Vaccine Efficacy

Expert analysis highlights that widespread population vaccination played a primary indirect role in reducing this overall thrombotic burden over time. Large-scale observational data from the IVY Network further indicate that completing an original monovalent mRNA vaccination series offered an overall 84% effectiveness in preventing COVID-19 hospitalizations associated with acute VTE.^2,3

Although early pandemic reports raised public concerns regarding potential vaccine-induced clotting, extensive clinical studies confirm that vaccination mitigates downstream inflammatory pathways, suppressing platelet and neutrophil activation without increasing acute thrombotic hazards.^1,3

Longitudinal survival analyses spanning 180 days post-infection reveal that the post-infectious risk of thrombosis and mortality is heavily concentrated within the first 60 days following acute illness. Beyond 8 weeks, event rates in both vaccinated and unvaccinated individuals plateau, returning toward baseline acute respiratory infection levels.¹

These temporal patterns provide vital clinical guidance for providers monitoring long-term thrombotic complications and evaluating lingering prothrombotic states linked with long COVID.

Pharmacist Leadership in Clinical Quality Management and Patient Care

For pharmacy professionals, these health outcomes arrive at a crucial moment as federal immunization recommendations undergo significant structural shifts. The CDC and the Advisory Committee on Immunization Practices (ACIP) recently transitioned COVID-19 vaccine guidance for adults and children from universal mandates to a shared clinical decision-making framework.⁴

Ongoing legal developments surrounding the 2026 childhood immunization schedule underscore the rapidly evolving regulatory landscape in which pharmacists must navigate patient consultations regarding immunization risk and protective benefits.

In addition to outpatient counseling, health-system pharmacists fulfill a critical operational role in optimizing hospital-wide thromboembolism prevention strategies. In a single-center study evaluating cardiothoracic surgical inpatients, structured pharmacist interventions utilizing automated clinical decision support software significantly increased standardized thromboembolism prophylaxis compliance from 57.1% to 77.8%.⁵

Dedicated daily case reviews and direct physician consultations conducted by pharmacists also elevated mechanical prophylaxis implementation from 54.6% to 79.7%, effectively closing guideline implementation gaps without increasing major bleeding events.

As clinical institutions align with national quality management benchmarks, pharmacists remain essential clinical leaders in tailoring risk-appropriate prophylaxis and safeguarding patient safety across diverse acute care settings.⁵

“Vaccination significantly reduced the risk of VTE and mortality in COVID-19 patients,” concluded authors of the current study.¹ “COVID vaccination was associated with a 59% reduced odds of both VTE and mortality within 30 days post-COVID-19. As of 2024, the clinical risk profile of COVID-19 has converged with that of other acute respiratory infections, particularly among vaccinated individuals.”

READ MORE: COVID-19 Resource Center

REFERENCES

1. Soff SP, Moffitt R, Sharathkumar A, et al. A comprehensive assessment of the impact of COVID variant and vaccination on venous thromboembolism and mortality. RPTH. 2026;10(3):103415. doi:10.1016/j.rpth.2026.103415

2. Neale T. VTE risk higher with COVID-19 than with flu. TCTMD. August 18, 2022. Accessed November 2, 2026. https://www.tctmd.com/news/vte-risk-higher-covid-19-flu

3. Hager DN, Zhu Y, Sohn I, et al. Effectiveness of the original monovalent messenger RNA coronavirus disease 2019 (COVID-19) vaccination series against hospitalization for COVID-19–associated venous thromboembolism. JID. 2024;231(2):378-385. doi:10.1093/infdis/jiae502

4. Changes to CDC vaccine recommendations in 2025 and 2026. Congressional Research Service. 2026. https://www.everycrsreport.com/files/2026-07-29_IN12684_1061cac2b508fd58a15d9fa7f034fb346cd54f96.pdf

5. Qiu S, Li D, Hu B, et al. The role of pharmacists in quality management of venous thromboembolism: a retrospective, observational, single-center study in the cardiothoracic surgery department. Front Pharmacol. 2026;17:1819628. doi:10.3389/fphar.2026.1819628