The Kaiser Permanente Vaccine Study Center helps ensure that the nation’s vaccines are safe and effective by conducting research to advance scientific understanding of vaccines at all levels of development.
- We study the safety and effectiveness of vaccines that the pharmaceutical industry is seeking to license.
- We partner with government agencies to monitor the safety and effectiveness of vaccines after they have been licensed.
- We examine the epidemiological factors important to developing and distributing new vaccines.
- We monitor influenza and other respiratory viruses and flu vaccine effectiveness.
Founded in 1985, the Kaiser Permanente Vaccine Study Center utilizes the potential of Kaiser Permanente’s large member population for vaccine efficacy and safety studies. Key studies have focused on Haemophilus influenza; pneumococcus; MMR (measles, mumps, rubella); chickenpox; rotavirus; and flu vaccines.
In collaboration with Kaiser Permanente’s Division of Research, we coordinate clinical trials of new vaccines at our medical facilities in Northern California. Our studies of new vaccines have led to licensing of vaccines to prevent diseases caused by Haemophilus influenza, pneumococcus, chickenpox, meningitis and flu.
Vaccine Study Center Team
| Nicola P. Klein, MD, PhD, FAAP | Director |
| Ousseny Zerbo, PhD | Research Scientist II |
| Karen Jacobson, MD, MPH | Research Scientist |
| Helena Archer, PhD, MPH | Postdoctoral Research Fellow |
| Amy Wiesner, RN, BSN, CCRC | Clinical Trial Administrative Director III |
| Kristin Burnett, MPH | Senior Research Project Manager |
| Lisa Powell, BS, MHA | Senior Research Project Manager |
| Sally Stephens, MPH | Senior Research Project Manager |
| John Hansen, MPH | Project Manager V |
| Amber H. Hyman, PhD, MPH | Project Manager V |
| Pat Ross, BA | Project Manager |
| Janelle Baires, MSN, RN | Clinical Research Nurse Manager |
| Latisha M. Burun, BSN, RN, CPN | Clinical Trial Research Nurse II |
| Courtney A. Oxandale, RN | Clinical Trial Research Nurse II |
| Charlie C. Chao, MA, CCRP | Clinical Trial Research Coordinator III |
| Debbie C. Jacobs, CCRC | Clinical Trial Research Coordinator III |
| Tia Myagmarjav, BS | Clinical Trial Research Coordinator I |
| Dominique Cabanero | Research Assistant |
Nicola P. Klein, MD, PhD, FAAP
Director
Nicola P. Klein, MD, PhD, is the director of the Kaiser Permanente Vaccine Study Center, which she joined as co-director in 2006. She is also a senior research scientist at the Kaiser Permanente Northern California Division of Research. Her research interests include vaccine safety and efficacy, genetic influences on vaccine responses, and vaccine responses among at-risk populations (premature infants and children with chronic or genetic diseases). She is the principal investigator of numerous vaccine safety studies, and has published widely on vaccine safety and efficacy in children and infants. She received her medical degree and her doctorate in biochemistry, as part of the Medical Scientist Training Program funded by the National Institutes of Health, at New York University School of Medicine. She completed her residency in pediatrics at the Lucile Salter Packard Children’s Hospital (LPCH) at Stanford University School of Medicine, and subsequently completed a Clinical Immunization Safety Assessment (CISA) Network Vaccine Safety Fellowship, sponsored by the Centers for Disease Control and Prevention, at Stanford. She is board certified in pediatrics and is a professor in the Department of Health Systems Science at the Kaiser Permanente Bernard J. Tyson School of Medicine.
Ousseny Zerbo, PhD
Research Scientist II
Ousseny Zerbo, PhD, is a Research Scientist in the Vaccine Study Center at Kaiser Permanente Northern California Division of Research. His research interest is in maternal vaccination during pregnancy and early childhood health outcomes, vaccine uptake, safety and effectiveness. He is the principal investigator on two NIH-funded projects to investigate the effectiveness of influenza vaccination, COVID-19 vaccination during pregnancy, and infant risk of influenza and COVID-19. He also studies risk factors associated with autism spectrum disorders. Prior to joining the Vaccine Study Center, he completed post-doctoral training in the Autism Research Program at the Division of Research. He received his PhD in epidemiology from the University of California, Davis and his bachelor’s degree in biological science and teaching credential from the University of Ouagadougou, Burkina Faso, West Africa.
Karen Jacobson, MD, MPH
Research Scientist
Dr. Karen Jacobson joined the Vaccine Study Center at the Kaiser Permanente Northern California Division of Research in 2023 as a Research Scientist. She is a board-certified Infectious Diseases physician. Dr. Jacobson obtained a bachelor of arts in Human Biology from Stanford University and a doctor of medicine and master of Public Health from the Icahn School of Medicine at Mount Sinai. She completed her residency training in Internal Medicine/HIV Primary Care at the Yale-New Haven Hospital and her fellowship in Infectious Diseases at Stanford. Dr. Jacobson’s research is focused on mitigating sequelae of infectious diseases, particularly SARS-CoV-2. She is co-Investigator of multiple outpatient studies of treatments for acute and convalescent SARS-CoV-2 disease, and her published work has described clinical and immunologic correlations of Long COVID and risk of post-vaccination infection with SARS-CoV-2 variants of concern.
Helena Archer, PhD, MPH
Postdoctoral Research Fellow
Helena Archer, PhD, MPH, joined the Vaccine Study Center at Kaiser Permanente Division of Research as a research post-doctoral fellow in 2024. Her research interests include the prevention of infections and severe disease in vulnerable populations, including identifying and addressing health disparities. Her recent work has focused on COVID-19 in state prisons and in communities exposed to environmental pollutants. Prior to joining DOR, Helena worked for several years in public health practice in the US and abroad before completing her MPH at the University of Washington and her PhD at University of California, Berkeley, both in Epidemiology.
Amy Wiesner, BSN, RN
Clinical Trial Administrative Director III
Kristin Burnett, MPH
Senior Research Project Manager
Kristin Burnett, MPH, joined the Kaiser Permanente Vaccine Study Center in 2025. Her responsibilities include project management of federally funded post-licensure vaccine safety and effectiveness studies and serving as VSC’s liaison to the CDC for its Vaccine Safety Datalink (VSD) portfolio. Before joining VSC, she served as Immunization Program Manager overseeing public immunization programs as well as Vaccine Technical Advisor during COVID-19 response for Contra Costa County’s public health department, and as a Section Chief overseeing vaccine equity programs during the COVID-19 pandemic for the California Department of Public Health’s Office of Health Equity. She received her Bachelor of Arts in Anthropology and Master of Public Health in Health & Social Behavior from the University of California, Berkeley.
Lisa Powell, BS, MHA
Senior Research Project Manager
Lisa Powell, BS, started with the Vaccine Study Center in 1991 as a research assistant. Currently, she is a research project manager. In her current role, she is responsible for taking care of the department’s HR needs, such as hiring and training. She also works closely with the administrative director to plan and coordinate the activities of all non-physician personnel nationally. In addition, she is the remote data manager, responsible for the data entry staff. In this role, she ensures that the data entry staff keeps the data entry flowing and completed in a timely manner, and she manages the queries for all the remote data entry studies.
Sally Stephens, MPH
Senior Research Project Manager
Sally Stephens, MPH, joined the Kaiser Permanente Vaccine Study Center in 2025 as a senior research project manager. Her responsibilities include project management of post-licensure and epidemiologic studies. Prior to joining VSC, she worked with the Institute of Global Health Science at the University of California, San Francisco, the Digital Initiatives Group at I-TECH at the University of Washington, and the San Francisco Department of Public Health. She earned her Bachelor of Science in Chemistry at the University of South Carolina and her Master of Public Health in Epidemiology at Emory University.
John Hansen, MPH
Project Manager V
John Hansen, MPH, has been a Kaiser Permanente Vaccine Study Center adverse event coordinator and project manager since 1993. He manages programmers and serves as project manager for post-marketing safety studies, his primary research interest. In his role as a project manager, his responsibilities include planning and coordinating with manufacturers to ensure the safety of vaccines that have been licensed and brought to market. In 2001-2003, he served as a member of the Brighton Collaboration Working Groups on Fever and lntussusception. He earned his bachelor’s in sociology and his master of public health, with a specialty in epidemiology/biostatistics, at the University of California, Berkeley.
Amber H. Hyman, PhD, MPH
Project Manager V
Amber H. Hyman, PhD, MPH, joined the Kaiser Permanente Vaccine Study Center in 2016 as a senior research project manager. Her responsibilities include project management for post-licensure and epidemiological studies. Before joining us, she worked as a research scientist at the International Vaccine Institute, focused on assessing the effectiveness of an oral cholera vaccine given to displaced populations in southern Malawi. She has also worked in academic research on chronic disease modeling and cost-effectiveness analysis of government assistance programs. She earned her bachelor of arts in public health and mass communications at the University of California, Berkeley, her master of public health (health policy) at Columbia University, and a PhD in public health at Technical University of Berlin.
Pat Ross, BA
Project Manager
Pat Ross has been with the Vaccine Study Center since 1997. In her initial position as a research assistant she began working with data cleaning vaccine injection logs, and worked extensively with research nurses. She moved on to become a research associate III, and is currently a project manager. Pat has worked extensively with the medical record analyst staff at Division of Research to complete chart review studies. Pat has designed and implemented data collection tools specific to studies’ requirements. She has helped evolve the data collection tools to paper-less Quick Review forms. During the COVID-19 pandemic, Pat worked extensively on programming data collection tools in RedCap. Pat continues to apply her RedCap programming skills on non-COVID-19 related studies. Pat graduated from UC Berkeley with a degree in English literature in 1992.
Janelle Baires, MSN, RN
Clinical Research Nurse Manager
Latisha M. Burun, BSN, RN, CPN
Clinical Trial Research Nurse II
Latisha ‘Tish’ Burun has been a Clinical Trials Research Nurse with the Vaccine Study Center since 2014. Tish provides regulatory management and study management support for our clinical trials. She began her career with us as a study site clinical research nurse in the Sacramento region. Before joining the Kaiser Permanente Vaccine Study Center team, Tish worked as a pediatric urology clinic nurse and a pediatric trauma charge nurse. Tish has a bachelor of science in nursing from California State University, Los Angeles, is licensed as a registered nurse in California, and holds a certification in pediatric nursing.
Courtney A. Oxandale, RN, BSN, CPN, CCRC
Clinical Trial Research Nurse II
Charlie C. Chao, MA, CCRP
Clinical Trial Research Coordinator III
Charlie C. Chao, MA, CCRP, has been with us since 2000 as a clinical trial research coordinator III. In this role, he supports Kaiser Permanente’s Principles of Responsibility; ensures compliance with procedures; maintains the security and confidentiality of participants’ data; reviews medical records and test results; and abstracts needed data per protocol requirements. He coordinates and prepares protocol specimens for shipping or storage in accordance with regulations and sponsor shipping guidelines; assists in study closure activities; and coordinates study vaccines storage and shipping. He works on federally funded projects including CDC’s Vaccine Safety Datalink and Clinical Immunization Safety Assessment and on clinical trial projects. Before joining us, he worked in an outpatient pharmacy at Kaiser Permanente, San Rafael.
Debbie C. Jacobs, CCRC
Clinical Trial Research Coordinator III
Debbie C. Jacobs, clinical trial research coordinator II, has been with us since 2004 coordinating clinical trial research tasks. She provides research, operational, and administrative support to the Kaiser Permanente Northern California principal investigators, the clinical trials administrative director, and other research staff members conducting multiple Food and Drug Administration-regulated clinical trials. Before joining our staff, she was a medical transcriptionist and medical office manager for a private practice.
Tia Myagmarjav, BS
Clinical Trial Research Coordinator I
Dominique Cabanero
Research Assistant
Dominique Cabanero joined the Vaccine Study Center in 2022 as a research assistant, and she provides support to our clinical trials and to other staff members within the VSC office. She joined the Vaccine Study Center after working for 12 years in the dental field. She currently studies healthcare management at SNHU and hopes to pursue a master’s degree in public health.
In Memoriam
Roger Paul Baxter, MD, FACP
Roger Paul Baxter, MD, FACP, was co-director of the Kaiser Permanente Vaccine Study Center from 2006 until his death in late 2016. As principal investigator for many studies of vaccines, biologics, and the epidemiology of infectious diseases, and the author of extensive studies on vaccine safety and effectiveness, he helped to build the reputation of the Vaccine Study Center as a national resource for vaccine research and expertise. Prior to joining the Vaccine Study Center and devoting himself full-time to research, Dr. Baxter practiced internal medicine and infectious diseases at Kaiser Permanente, Oakland for 15 years. Board certified in both internal medicine and infectious diseases, he led the Kaiser Permanente Influenza Vaccination Program, helping to ensure yearly vaccination for more than 1 million members, and directed Kaiser Permanente’s influenza surveillance program for more than 13 years. In 2014, he received the Morris F. Collen Research Award for “answering critical questions about vaccine safety and effectiveness to the benefit of people around the globe.”
DOR Programming and Analytical Staff
| Maqdooda Merchant, MSc | Senior Manager, Data Reporting and Analytics, Biostatistics |
| Sharareh Modaressi, MD, MPH | Data Reporting and Analytics Consultant V, Biostatistics |
| Heather Forquer, MPH | Data Scientist V, Biostatistics |
| Lauren Liao, PhD | Biostatistician |
| Karen C. Valdez Nunley, MS | Data Reporting and Analytics Consultant, Biostatistics |
| Julius Timbol, BS, MS | Data Reporting and Analytics Consultant, Biostatistics |
| Lawrence Block, MPH | Data Reporting and Analytics Consultant IV, Biostatistics |
| Thomas K. Leong, MS | Data Reporting and Analytics Consultant IV, Biostatistics |
| Andrew Watson | Data Reporting and Analytics Consultant II |
| Medical Record Analysts |
Maqdooda Merchant, MSc
Manager, Data Reporting and Analytics, Biostatistics
Maqdooda Merchant joined us in July 2022 as Manager, Data Reporting and Analytics, Biostatistics. She manages the VSC data and supports the VSC programmers including administrative duties as well as participating in analyst recruitment. Prior to joining us she managed the analysts in DOR’s Bio-Statistical Consulting Unit providing research support from IRB proposal to data extraction, analysis, and publication for the GME Residency Research program as well as Community Health Research. She is Epic-certified in EpicCare Ambulatory and contributed to training materials as well as provided regional training on Clarity, testing of KPBINC custom views as well as the DOR Research Database. Prior to joining DOR, she was a lead analyst for various TPMG clinical guidelines as well as HEDIS and Quality Goal Measures. She has an MA in applied statistics from UCSB and an MSc in probability & statistics from the University of Bombay, India.
Sharareh Modaressi, MD, MPH
Data Reporting and Analytics Consultant, Biostatistics
Sharareh Modaressi joined us in 2016 as a senior data consultant with responsibilities for data analysis using SAS software on various platforms: mainframe, PC and UNIX. Before joining us, she spent more than twelve years of data consulting and analytical experience in Kaiser Permanente Northern California’s Quality Operation and Support Department. She is the original developer of GYN model and ICD10 tools for Kaiser Permanente. She has a master of public health from the University of California, Berkeley and a MD degree (with a specialty in infectious disease) from the University of Shahid Beheshti in Tehran/Iran.
Heather Forquer, MPH
Data Scientist V, Biostatistics
Heather Forquer joined the Vaccine Study Center in 2023 as a data scientist working on vaccine safety and effectiveness studies. She joined Kaiser Permanente in 2015 and has contributed to multiple teams, including operations teams focused on evaluating models of care and research teams studying neonatal and pregnancy-related health conditions. Prior to Kaiser Permanente, she worked at the California Department of Public Health in maternal and child health epidemiology and the University of Pennsylvania in health communications research. She earned a Master of Public Health degree from the University of Pennsylvania.
Lauren Liao, PhD
Biostatistician
Lauren Liao, PhD, is a biostatistician in the Vaccine Study Center at Kaiser Permanente Northern California Division of Research. Her methodological research focuses on areas of causal study design and analysis in observational and trial settings. She is an active researcher in ongoing studies in vaccine effectiveness, safety, and coverage. Prior to joining the Vaccine Study Center, she earned her PhD in Biostatistics from the University of California, Berkeley. She received her Master’s in Biostatistics also from University of California, Berkeley and her Bachelor’s in Probability and Statistics from University of California, San Diego.
Karen C. Valdez Nunley, MS
Data Reporting and Analytics Consultant, Biostatistics
Karen Nunley joined Kaiser Permanente Vaccine Study Center in 2015 as a senior data consultant with responsibilities for data management and programming using SAS software. She joined Kaiser Permanente in 2005 within Management Information and Analysis, where she worked on performance reporting, DxCG risk scores, and utilization datasets. She later joined Charles Schwab as a senior database marketing manager, responsible for retirement participant campaigns. She returned to Kaiser Permanente in Quality and Operations Support and focused on specialty care access reporting and data analytics. Karen holds a bachelor’s degree in computer science from Ateneo de Manila University, and a master of science in information systems from University of San Francisco.
Julius Timbol, BS, MS
Data Reporting and Analytics Consultant, Biostatistics
Julius Timbol joined us in 2010 as a senior data consultant (vaccine programmer/analyst) with responsibilities for data analysis using SAS software on various platforms: mainframe, PC environment, and UNIX. Before joining us, he spent four years doing SAS programming in Kaiser Permanente Northern California’s Quality Operation and Support Department and seven years at CTB/McGraw-Hill programming for psychometricians in educational test designs and analyses, incorporating statistical methods found in item response theory. He enjoys programming statistical or mathematical algorithms. Outside of work, his passions include flying airplanes upside down, participating in aerobatic competitions, and scuba diving. He earned a bachelor of science in mathematics from San Diego State University and a master of science in statistics from California State University, Hayward.
Lawrence Block, MPH
Data Reporting and Analytics Consultant IV, Biostatistics
Lawrence Block joined us in 2024 as a Senior Data Consultant, specializing in data extraction and analysis. Before joining our team, he spent over 11 years as a data consultant and analyst in Kaiser Permanente Northern California’s Quality Operations and Support Department and Division of Research. His work at Kaiser focused on hospital-acquired illnesses, perinatal care, and infectious diseases. Prior to his tenure at Kaiser Permanente, Lawrence worked as an analyst specializing in infection control at the University of California, San Francisco (UCSF) Medical Center. Lawrence holds a Bachelor of Science degree from the Rochester Institute of Technology, a Master’s degree in Public Administration from John Jay College of Criminal Justice, and a Master of Public Health (with a specialization in epidemiology) from the University of California, Los Angeles (UCLA).
Thomas K. Leong, MS
Data Reporting and Analytics Consultant IV, Biostatistics
Thomas K. Leong joined the Vaccine Study Center in 2024 and is primarily involved with conducting data management and analysis, as well as providing investigator support on data sources, methods and reporting. Prior to joining the VSC, he worked on data analysis for other Division of Research projects focusing on cardiovascular disease and renal disease. He has also worked on developing data management programs for use in marginal structural modeling and is active in workgroups of the wider Programmer Analyst Group at DOR. Thomas holds a bachelor’s degree from Cornell University and a master’s degree from the University of California, Berkeley.
Andrew Watson
Data Reporting and Analytics Consultant II
Andrew Watson joined the Vaccine Study Center in 2022 as a data consultant, contributing to COVID-19 and RSV studies through analysis using SAS, Python, and R. With a background in education, he previously served as a teacher and then as a data analyst for Chicago Public Schools. Andrew holds a bachelor’s degree in biology and Spanish from Washington University in St. Louis, as well as master’s degrees in teaching from Dominican University and in data science from Northwestern University.
Medical Record Analysts
Sandy Bauska, RHIT
Virginia Robinson
Margarita Magallon RHIT, CPC
VSC Clinical Sub-Investigators
Site: Daly City
Study Nurse: Lorrie Lowe, RN, BNS
Phone Number: 650-301-4535
Sub-Investigator: Sandra Lee, MD
Site: Oakland
Study Nurse: Carlos Tapia, RN
Phone Number: 510-752-7846
Sub-Investigators: Katrina Saba, MD, and Suresh Rangarajan, MD
Site: Roseville
Study Nurses:
Mary Day, RN
Phone Number: 916-787-6490
Ludy Lemus, RN
Phone Number: 916-787-6583
Sub-Investigator: Kenneth Hempstead, MD
Site: Sacramento – Point West
Study Nurse: Christine Cash, RN, BSN
Phone Number: 916-614-4858
Sub-Investigator: David Cooper, MD
Site: Santa Clara
Study Nurse: Sally Upadhyaya, RN, CCRC
Phone Number: 408-851-1167
Sub-Investigator: Kenneth Purdy, MD
Site: South Sacramento
Study Nurse: Charmaine Que, RN
Phone Number: 916-688-6790
Sub-Investigator: Nicole Makram, MD
Site: Walnut Creek
Study Nurse: Jolynne Encarnacion, RN
Phone Number: 925-295-5129
Sub-Investigator: Kristen Lum, MD
Site: San Jose
Study Nurse: Douglas Ernst, RN, BSN, CPN, CCRC
Doug joined the Vaccine Study Center in 2020 as a travel nurse with the Pfizer Covid trial in Santa Clara. Doug became a permanent staff member in January 2022, first staying in Santa Clara then changing sites and moving to San Jose in September 2023. Prior to joining the Vaccine Study Center, he was a pediatric nurse for 15 years, travel nursing for 8 of those years. Doug has a Bachelor of Arts degree in Psychology from the University of Nebraska-Lincoln, and a Bachelor of Science degree in Nursing from Creighton University. He holds certificates in pediatric nursing as well as Certified Clinical Research Coordinator.
Phone Number: 408-972-6159
Sub-Investigator: Tuan Huynh, MD
Dr. Huynh attended University of California San Diego for undergraduate studies and University of California Irvine for medical school and residency training. Dr. Huynh has been board certified in pediatrics since 1996, when he joined Kaiser Permanente. Dr. Huynh’s interests are in all aspects of pediatrics, particularly neonatology, and he has been a sub-investigator with the Kaiser Permanente vaccine research program for more than 20 years. Dr. Huynh has also served as assistant chief of Outpatient Pediatrics and chief of Inpatient Pediatrics in the past, and was Neonatal Resuscitation Program instructor, chair of the Perinatal Committee, and Physician Quality Coordinator.
