Westyn Branch-Elliman

2026

Severe outcomes of individual or multiple respiratory viral infections in a large national healthcare system, 2022-2023.

Janet M. Grubber^†, Ikwo K. Oboho^†, Kaitlin N. Swinnerton, Theodore C. Feldman, Nhan V. Do, Nathanael R. Fillmore, Westyn Branch-Elliman^‡, Paul A. Monach^‡† Equal first authorship · ^‡ Equal senior authorship

Frontiers in Public Health14, 1808528

U.S. Veterans and VA Data COVID-19 Logistic Regression Acute Respiratory Viral Infections Immunosuppressive Therapy

2025

Leveraging near-real-time patient and population data to incorporate fluctuating risk of severe COVID-19: development and prospective validation of a personalised risk prediction tool.

Kaitlin Swinnerton^†, Nathanael R. Fillmore^†, Austin Vo, Jennifer La, Danne Elbers, Mary Brophy, Nhan V. Do, Paul A. Monach^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

eClinicalMedicine81, 103114

U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Severe COVID-19 Predictive Modeling

2025

Pulmonary aspergillosis in US Veterans with COVID-19: a nationwide, retrospective cohort study.

Kaitlin Swinnerton^†, Nathanael R. Fillmore^†, Ikwo Oboho, Janet Grubber, Mary Brophy, Nhan V. Do, Paul A. Monach^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

Antimicrobial Stewardship & Healthcare Epidemiology5(1), e28

U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records COVID-19 Risk Factors

2024

Longitudinal trends in 30-day mortality attributable to SARS-CoV-2 among vaccinated and unvaccinated US veteran patients.

Caitlin A. Trottier^†, Jennifer La^†, Lucy Li, Nathanael R. Fillmore, Paul A. Monach, Shira Doron^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

Infection Control and Hospital Epidemiology45(3), 393-395

U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records COVID-19 Mortality Prediction

2024

Severe COVID-19 in Vaccinated Adults With Hematologic Cancers in the Veterans Health Administration.

Sonia T. Anand, Austin D. Vo, Jennifer La, Nhan V. Do, Nathanael R. Fillmore, Mary Brophy, Westyn Branch-Elliman, Paul A. Monach

JAMA Network Open7(2), e240288

U.S. Veterans and VA Data Case-Control Study Electronic Health Records COVID-19 Severe COVID-19

2024

Risk of severe coronavirus disease 2019 despite vaccination in patients requiring treatment with immune-suppressive drugs: A nationwide cohort study of US Veterans.

Sonia T. Anand, Austin D. Vo, Jennifer La, Mary Brophy, Nhan V. Do, Nathanael R. Fillmore, Westyn Branch-Elliman, Paul A. Monach

Transplant Infectious Disease26(1), e14168

U.S. Veterans and VA Data Electronic Health Records COVID-19 Severe COVID-19 Vaccine Effectiveness

2024

Underuse of Antiviral Drugs to Prevent Progression to Severe COVID-19 - Veterans Health Administration, March-September 2022.

Paul A. Monach, Sonia T. Anand, Nathanael R. Fillmore, Jennifer La, Westyn Branch-Elliman

MMWR: Morbidity and Mortality Weekly Report73(3), 57-61

U.S. Veterans and VA Data COVID-19 Severe COVID-19 Antiviral Therapy Hematologic Malignancies

2023

Even after SARS-CoV-2 booster, there is increased COVID-19 breakthrough infection in patients with plasma cell disorders.

Nathanael R. Fillmore, Jennifer La, Julie Tsu-Yu Wu, June K. Corrigan, Westyn Branch-Elliman, Paul Monach, Mary T. Brophy, Nhan V. Do, Nikhil C. Munshi

Blood Advances7(21), 6767-6770

U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records Multiple Myeloma COVID-19

2023

Maintaining the Utility of Coronavirus Disease 2019 Pandemic Severity Surveillance: Evaluation of Trends in Attributable Deaths and Development and Validation of a Measurement Tool.

Caitlin Trottier^†, Jennifer La^†, Lucy L. Li^†, Majd Alsoubani, Austin D. Vo, Nathanael R. Fillmore, Westyn Branch-Elliman, Shira Doron^‡, Paul A. Monach^‡† Equal first authorship · ^‡ Equal senior authorship

Clinical Infectious Diseases77(9), 1247-1256

COVID-19 U.S. Veterans and VA Data Logistic Regression Model Validation Pandemic Surveillance

2023

Coronavirus disease 2019 (COVID-19) hospitalization metrics that do not account for disease severity underestimate protection provided by severe acute respiratory coronavirus virus 2 (SARS-CoV-2) vaccination and boosting: A retrospective cohort study.

June K. Corrigan^†, Jennifer La^†, Nathanael R. Fillmore, Nhan V. Do, Mary Brophy, Shira Doron, Paul A. Monach^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

Infection Control and Hospital Epidemiology44(1), 149-151

U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records COVID-19 Vaccine Effectiveness

2022

Factors associated with the speed and scope of diffusion of COVID-19 therapeutics in a nationwide healthcare setting: a mixed-methods investigation.

Jennifer La^†, Nathanael R. Fillmore^†, Nhan V. Do, Mary Brophy, Paul A. Monach^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

Health Research Policy and Systems20(1), 134

COVID-19 U.S. Veterans and VA Data Retrospective Cohort Study Mixed-Methods Investigation Clinical Practice Diffusion

2022

The COVID-19 hospitalization metric in the pre- and postvaccination eras as a measure of pandemic severity: A retrospective, nationwide cohort study.

Nathanael R. Fillmore^†, Jennifer La^†, Chunlei Zheng, Shira Doron, Nhan V. Do, Paul A. Monach^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

Infection Control and Hospital Epidemiology43(12), 1767-1772

U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Vaccine Effectiveness Hospitalization Metrics

2022

Recent common human coronavirus infection protects against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection: A Veterans Affairs cohort study.

Nathanael R. Fillmore, Raphael E. Szalat, Jennifer La, Westyn Branch-Elliman, Paul A. Monach, Vinh Nguyen, Mehmet K. Samur, Mary T. Brophy, Nhan V. Do, Nikhil C. Munshi

PNAS119(46), e2213783119

U.S. Veterans and VA Data Retrospective Cohort Study Electronic Health Records COVID-19 Cox Proportional Hazards Model

2022

Factors Associated With Severe COVID-19 Among Vaccinated Adults Treated in US Veterans Affairs Hospitals.

Austin D. Vo^†, Jennifer La^†, Julie T-Y Wu, Judith M. Strymish, Matthew Ronan, Mary Brophy, Nhan V. Do, Westyn Branch-Elliman^‡, Nathanael R. Fillmore^‡, Paul A. Monach^‡† Equal first authorship · ^‡ Equal senior authorship

JAMA Network Open5(10), e2240037

U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Severe COVID-19 Risk Factors

2022

Increased COVID-19 breakthrough infection risk in patients with plasma cell disorders.

Jennifer La^†, Julie Tsu-Yu Wu^†, Westyn Branch-Elliman, Linden Huhmann, Summer S. Han, Mary Brophy, Nhan V. Do, Albert Y. Lin, Nathanael R. Fillmore^‡, Nikhil C. Munshi^‡† Equal first authorship · ^‡ Equal senior authorship

Blood140(7), 782-785

U.S. Veterans and VA Data Electronic Health Records Multiple Myeloma COVID-19 Vaccine Effectiveness

2022

Impact of prior SARS-CoV-2 infection on incidence of hospitalization and adverse events following mRNA SARS-CoV-2 vaccination: A nationwide, retrospective cohort study.

Lucy L. Li^†, Chunlei Zheng^†, Jennifer La, Nhan V. Do, Paul A. Monach, Judith M. Strymish, Nathanael R. Fillmore^‡, Westyn Branch-Elliman^‡† Equal first authorship · ^‡ Equal senior authorship

Vaccine40(8), 1082-1089

U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Vaccine Effectiveness mRNA Vaccines

2022

Association of COVID-19 Vaccination With SARS-CoV-2 Infection in Patients With Cancer: A US Nationwide Veterans Affairs Study.

Julie Tsu-Yu Wu^†, Jennifer La^†, Westyn Branch-Elliman, Linden B. Huhmann, Summer S. Han, Giovanni Parmigiani, David P. Tuck, Mary T. Brophy, Nhan V. Do, Albert Y. Lin^‡, Nikhil C. Munshi^‡, Nathanael R. Fillmore^‡† Equal first authorship · ^‡ Equal senior authorship

JAMA Oncology8(2), 281-286

U.S. Veterans and VA Data Retrospective Cohort Study COVID-19 Vaccine Effectiveness Cancer Patients