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Oregon Immunization Program Research Staff

Meet Our Research Staff

The Oregon Immunization Program works to keep Oregon healthy. From health educators to epidemiologists, our staff aims to reduce the incidence of vaccine-preventable disease through education and the promotion of public health best practices.

Our work extends beyond this community, however. Articles written by our staff have appeared in a variety of prestigious national publications, including the American Journal of Epidemiology, the New England Journal of Medicine, and the Journal of Pediatrics. These articles showcase the extensive research the scientists conducted in exploring a myriad of public health topics.

Click on a name to learn about our staff and view their publications.

Steve Robison is a national expert on immunization surveillance and vaccine effectiveness. While working for the Oregon Immunization Program, Steve has pioneered numerous approaches to using immunization registry data in support of public health. He is an author of 15 recent articles in peer-reviewed journals, including four articles in Pediatrics, and is a peer-reviewer for eight public health and medical journals. Steve is also a life-long bicycle commuter, and believes in staying out of crowds during influenza season.


  1. Changes in Influenza Vaccination Rates Following Withdrawal of Live Vaccine. Steve G Robison, Aaron Dunn, Deborah Richards, & Richard Leman. Pediatrics (October  2017)
  2. The Concordance of Parent and Child Immunization. Steve G Robison & Andrew Osborn. Pediatrics (April 2017)
  3. The Timing of Unvaccinated Pediatric Pertussis Cases in an Outbreak Year- Oregon 2012. Steve G Robison & Juventila Liko. Journal of Pediatrics (Jan 2017)
  4. Impact of Immunizing Pharmacists on Adolescent Influenza Immunizations. Steve G. Robison. Journal of the American Pharmacists Association (July/August 2016).
  5. NIS vs. Immunization Registry Measles Rates for Counties in Oregon.  Steve G. Robison: Public Health Reports (2016)
  6. Differences in Pertussis Incidence by Income among Oregon Teens during an Outbreak. Steve G. Robison, Juventila Liko, Paul Cieslak; Journal of Vaccines, (2015)
  7. Addressing Immunization Registry Population Inflation in Adolescent Immunization Rates. Steve G. Robison: Public Health Reports (2015)
  8. Sick-Visit Immunizations and Delayed Well-Baby Visits. Steve G. Robison: Pediatrics (2013). 
  9. Incomplete Early Childhood Immunization Series and Missing Fourth DTaP Immunizations; Missed Opportunities or Missed Visits? Steve Robison: ISRN Preventive Medicine (2013).
  10. Frequency of Alternative Immunization Schedules in a Metropolitan Area. Steve Robison, Holly Groom & Collette Young:  Pediatrics (2012).
  11. Risk Factors Associated with Parents Claiming Personal-Belief Exemptions to School Immunization Requirements: Community and Other Influences on More Skeptical Parents in Oregon. James Gaudino & Steve Robison: Vaccine (2012).
  12. Immunization Milestones: A More Comprehensive Picture of Age-Appropriate Vaccination. Steve  Robison, Samantha  Kurosky, Collette Young, Charles Gallia, Susan Arbor: Journal of Biomedicine and Biotechnology (2010).

Juventila Liko is an epidemiologist with the Oregon Public Health Division Immunization Program, and specializes in vaccine preventable diseases. In this position, she works closely in collaboration with the Acute and Communicable Disease Prevention Program, for which she provides rotational outbreak and epidemiology services to local health departments and clinicians.

She received her medical degree from University of Tirana in Albania. During her 10 year tenure as a pediatrician at the University Hospital Centre “Mother Teresa” in Tirana, she had firsthand experience with different vaccine preventable diseases such as tetanus, diphtheria, pertussis, measles, mumps , rubella, meningitis and even polio. In turn, she is a strong advocate for vaccination. Before coming to the U.S. she was awarded a fellowship in pediatrics from the Catholic University of Leuven in Belgium. While working in Belgium she participated in research activities focusing on the epidemiological aspects of infectious diseases in children. In 2002, she received a Master of Public Health from University of Utah. While in Utah, she worked with underserved populations as an AmeriCorps volunteer. She also did volunteer work with Kosovo refugees through UNHCR during the Yugoslavian crisis in 1999.

She is a co-principal investigator on federally funded grants focusing on the epidemiology of pertussis and evaluation of pertussis vaccination in Oregon. Juventila has published in peer-reviewed journals on topics such as measles, pertussis, parapertussis and norovirus. She lives with her family in Portland, Oregon, and enjoys an active lifestyle, including running, camping, cooking and traveling.


  1. Do Pertussis Vaccines Protect Against Bordetella Parapertussis? Juventila Liko, Steve Robison, Paul Cieslak. Clinical Infectious Disease (March 2017) 
  2. The Timing of Unvaccinated Pediatric Pertussis Cases in an Outbreak Year - Oregon 2012. Steve G Robison and Juventila Liko. Journal of Pediatrics (Jan 2017)
  3. An assessment of the Cocooning Strategy for Preventing Infant Pertussis-United States, 2011. Blain AE, Lewis M, Banerjee E, Kudish K, Liko J, McGuire S, Selvage D, Watt J, Martin SW, Skoff TH. Clinical Infectious Disease (Dec 2016 
  4. Risk Factors for Pertussis Among Hispanic Infants: Metropolitan Portland, Oregon, 2010-2012. Levri KM, Reynolds L, Liko J, Dott M, Robinson BF, Cieslak PR. Pediatric Infectious Disease (May 2016) 
  5. Notes from the Field: Subacute Sclerosing Panencephalitis Death - Oregon, 2015. Liko J, Guzman-Cottrill JA, Cieslak PR. MMWR. Morbidity Mortality Weekly Report (Jan 2016) 
  6. Sources of Infant Pertussis Infection in the United States. Skoff TH, Kenyon C, Cocoros N, Liko J, Miller L, Kudish K, Baumbach J, Zansky S, Faulkner A, Martin SW. Pediatrics (October 2015) 
  7. Suffer the Infants: A Severe Case of Pertussis in Oregon, 2012. Liko J, Koenig WJ, Cieslak PR. Public Health Reports (Sep, Oct 2015) 
  8. Differences in Pertussis Incidence by Income among Oregon Teens during an Outbreak. Steve G. Robison, Juventila Liko, Paul Cieslak; Journal of Vaccines, (2015)
  9. Pertussis vaccine performance in an epidemic year-Oregon, 2012. Liko J, Robison SG, Cieslak PR. Clinical Infectious Diseases (July 2014) 
  10. Waning immunity to pertussis following 5 doses of DTaP. Tartof SY, Lewis M, Kenyon C, White K, Osborn A, Liko J, Zell E, Martin S, Messonnier NE, Clark TA, Skoff TH. Pediatrics (April 2013) 
  11. Priming with whole-cell versus acellular pertussis vaccine. Liko J, Robison SG, Cieslak PR. New England Journal of Medicine (Feb 2013) 
  12. Use of templates to identify source of norovirus outbreak. Liko J, Keene WE. Emerging Infectious Disease (May 2009) 
  13. Asthma and allergy in Albania and the UK. Priftanji A, Strachan D, Burr M, Sinamati J, Shkurti A, Grabocka E, Kaur B, Fitzpatrick S. Lancet. (Oct 2001

Aaron Dunn graduated cum laude with a B.A. in Religious Studies at Westmont College in 1998. He then completed a M.A. in Public Health at the University of North Carolina, Greensboro. While working at Wake Forest University Health Sciences, Aaron coordinated NIH grants and clinical trials. Aaron then moved to OHSU where he developed a research program at the Oregon State Hospital and revamped the hospital’s IRB. While employed at OSH and now at the Oregon Immunization Program, Aaron has emphasized research ethics and data governance. He has been a secondary author on 15 scholarly articles on topics ranging from depression and sleep to immunizations.


  1. Changes in Influenza Vaccination Rates Following Withdrawal of Live Vaccine. Robison S, Dunn A, Richards D, Leman R. Pediatrics. Accepted for publication. 2017 Aug 21.

Rex Larsen has been with the Oregon Immunization Program since 2012, first as a public health educator, and now as the Quality Improvement Program Manager. He attended Portland State University and was awarded a BS in Public Health and Exercise Science. Before coming to the immunization program Rex worked in a variety of public health settings including primary prevention, and residential psychiatric facilities. As the Quality Improvement Program Manager Rex is one of the program’s subject matter experts on immunization data and quality improvement, and has worked extensively at the provider and health system levels to improve immunization rates in Oregon.


  1. A stepped-wedge cluster randomized trial designed to improve completion of HPV vaccine series and reduce missed opportunities to vaccinate in rural primary care practices
    Patricia A. Carney , Brigit Hatch , Isabel Stock , Caitlin Dickinson , Melinda Davis , Rex Larsen , Steele Valenzuela , Miguel Marino, Paul M. Darden , Rose Gunn , Laura Ferrara and Lyle J. Fagnan (2019)
  2. Implementing a Multipartner HPV Vaccination Assessment and Feedback Intervention in an Integrated Health System. Groom HC1, Irving SA, Caldwell J, Larsen R, Beaudrault S, Luther LM, Naleway AL. Journal of Public Health Management and Practice (November 2017)

​Dr. Paul Cieslak earned both his bachelor and medical degrees at The Ohio State University, finishing the latter in 1986. He trained in internal medicine at the University of Washington in Seattle and then completed a fellowship in infectious diseases at Washington University in St. Louis, with his research focused on amebiasis. During 1992–1994 he worked as an Epidemic Intelligence Service officer in the Foodborne and Diarrheal Diseases Branch of the Centers for Disease Control in Atlanta. While there, he investigated outbreaks of E. coli O157 infection, salmonellosis, shigellosis, cholera, and botulism; and he also researched the association between reptiles and infection with certain serotypes of Salmonella.

To learn something about public health at the state level, Dr. Cieslak came to Oregon as a CDC preventive medicine resident in 1994. Afterwards, he stayed on to direct the State Public Health Division’s communicable disease epidemiology section and Oregon’s Emerging Infections Program. During 1997–2011 he served on CDC’s Advisory Committee on Immunization Practices. Since July 2014 he has served as Medical Director for the Oregon Public Health Division’s Communicable Disease and Immunization programs. Dr. Cieslak has published articles on amebiasis, E. coli O157 infection, vancomycin use, Clostridium difficile infection, severe Group A strep infections, shigellosis, chickenpox, hepatitis C, norovirus, hospital-associated infections, and pertussis.

He holds adjunct clinical faculty positions with OHSU’s Department of Public Health and Preventive Medicine and Division of Infectious Diseases; and for the past 15 years has been a member of the Portland Guild of the Catholic Medical Association. One weekend a month he sees patients in infectious disease consultation for Legacy System and PeaceHealth hospitals. In 1988, Dr. Cieslak married a gal from Enterprise, Oregon; they have 6 children and live in northeast Portland, where they are active members of St. Rose Parish.


  1. Impact of the US Maternal Tetanus, Diphtheria, and Acellular Pertussis Vaccination Program on Preventing Pertussis in Infants <2 Months of Age: A Case-Control Evaluation. Skoff TH, Blain AE, Watt J, et al. Clinical Infectious Disease (2017). 
  2. Tracking Pertussis and Evaluating Control Measures through Enhanced Pertussis Surveillance, Emerging Infections Program, United States. Skoff TH, Baumbach J, Cieslak PR. Emerging Infectious Disease (2015);21:1568-73. 
  3. Notes from the field: fatal yellow fever vaccine-associated viscerotropic disease--Oregon, September 2014. DeSilva M, Sharma A, Staples E, et al. MMWR Morbidity Mortality Weekly Report (2015);64:279-81. 
  4. Vaccinated children and adolescents with pertussis infections experience reduced illness severity and duration, Oregon, 2010-2012. Barlow RS, Reynolds LE, Cieslak PR, Sullivan AD. Clinical Infectious Diseases (2014);58:1523-9. 
  5. Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies: recommendations of the advisory committee on immunization practices. Rupprecht CE, Briggs D, Brown CM, et al. MMWR Recomm Rep (2010);59:1-9. 
  6. Evidence for a 4-dose vaccine schedule for human rabies post-exposure prophylaxis in previously non-vaccinated individuals. Rupprecht CE, Briggs D, Brown CM, et al.  Vaccine (2009);27:7141-8. 
  7. Vaccine-era varicella epidemiology and vaccine effectiveness in a public elementary school population, 2002-2007. Lee LE, Ho H, Lorber E, Fratto J, Perkins S, Cieslak PR. Pediatrics (2008);121:e1548-54.">

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