Faculty Member

Natasha Sarah Crowcroft MA(Cantab), MSc, MD(PhD), MRCP, FFPH

Email Address(es)
Office Phone
647 260 7401
Office Address
Public Health Ontario 480 University Avenue, Suite 300 Toronto, Ontario M5G 1V2
Epidemiology Division
Clinical Public Health Division
Associate Professor
SGS Status
Full Member
Appointment Status
Status Only

Research Interests

  • Vaccination programmes and vaccine preventable diseases
  • Rabies
  • Diphtheria, Tetanus, Pertussis, meningococcal disease
  • Hepatitis A
  • Vaccination coverage
  • Encephalitis
  • Surveillance
  • Infectious disease epidemiology
  • Ethnicity and health

Education & Training History

1998-Dec 2005 Doctor of Medicine, (PhD equivalent) Murray Edwards (formerly New Hall) College, University of Cambridge. Thesis: Estimating the burden of Bordetella pertussis infection presenting to paediatric intensive care units and wards in London to inform vaccination policy in the United Kingdom. Oct 1992 –June 1994 Master of Science, MSc, Department of Public Health Sciences, St Georges Hospital Medical School, University of London. Master’s thesis: The social origins of infantile colic. Oct 1981-June 1987 Medical Degree, MB BS (Medicinae Baccalaureus, Baccalaureus Chirurgiae) United Medical Schools of Guy’s and St Thomas’, University of London Oct 1981-May 1984 Bachelor of Arts, BA (Cantab) Natural sciences, Part II Pathology, Murray Edwards (formerly New Hall) College, University of Cambridge, Cambridge UK. Postgraduate, Research and Speciality Training Oct 1995-Dec 1999 Specialist medical training in Public Health Medicine, Public Health Laboratory Service Communicable Disease Surveillance Centre, London UK Oct 1995-Sept 1997 Training in Field Epidemiology in the European Programme for Intervention Epidemiology Training (EPIET) based at the Institute for Hygiene and Epidemiology in Brussels, Belgium Feb 1992-Oct 1995 Specialist medical training in Public Health Medicine, South West Thames Regional Health Authority, London UK

Other Affiliations

Dr. Crowcroft’s primary appointment is in Laboratory Medicine and Pathobiology

Primary Teaching Responsibilities

Co-Director: Scientific Overviews, Dalla Lana School of Public Health

Professional Summary & Appointments

Natasha Crowcroft provides leadership for Applied Immunization Research, a cross-organizational scientific initiative, at Public Health Ontario (PHO). She was formerly the Chief of Infectious Diseases (2012-15) and Scientific Director of Surveillance and Epidemiology (2008-2012) at PHO. She has published over 175 articles and has international experience working at the World Health Organization (WHO) and the Pan-American Health Organization (PAHO). Dr. Crowcroft was a member of the Canadian National Advisory Committee on Immunization (NACI) from 2008-2013. She received her medical qualifications and masters of science from the University of London and doctorate in medicine (medical PhD) from the University of Cambridge.  Her research activities are designed to answer applied public health questions on infectious diseases and immunization. Globally Dr. Crowcroft has impact through giving technical advice to the World Health Organization (WHO) and Pan American Health Organization (PAHO). A successful track record includes more than 175 published articles and h-index of 32 as of October 2015. Dr. Crowcroft is the PI in the $6 million CIHR-funded Canadian Immunization Research Network (CIRN) launched in 2014.

Research Projects

Dr. Crowcroft has a significant role in developing advice and professional guidance on immunization and strengthening of related national structures and processes. She was a member of the National Advisory Committee on Immunization (NACI) from 2008-13. In 2011-14 she was a member of a task group to review The National Immunization Strategy and make recommendations on how Canada should build on its successes. The work resulted in a set of recommendations for the Public Health Network Council on all aspects of immunization in Canada, including research and evaluation. As part of this review, Dr. Crowcroft co-chaired a pilot process for the development of recommendations on a new Serogroup B meningococcal vaccine. These activities preceded and contributed to the establishment of the Canadian Immunization Research Network (CIRN) that was launched in 2014.

Dr. Crowcroft is a member of the International Expert Committee on the Documentation and Verification of measles, rubella and congenital rubella syndrome for the Pan American Health Organization (PAHO). She was part of the team conducting an in-country assessment of Haiti in 2012. In addition, she was a member of the team conducting assessments for Brazil in 2013-15 and giving advice in order to bring a measles outbreak to an end. Dr. Crowcroft is a co-signatory to the 2015 PAHO declaration certifying rubella elimination in the America. For WHO, she is a member of the measles and rubella working group of the Strategic Advisory Group of Experts, and chair of the measles and rubella surveillance and monitoring subcommittee.

The following are examples of research that has impacted thinking, policy and practice in the field:

  • Burden of pertussis: Dr. Crowcroft provided methodology reviews for the World Health Organization (WHO) for estimating burden for a number of vaccine preventable diseases, including pertussis, tetanus and neonatal tetanus and Millennium Development Goals on diphtheria, tetanus and pertussis. She developed the methods for WHO to estimate pertussis burden in 2000 for the Global Burden of Disease report. This became the standard method.
  • Causes and investigation of Encephalitis: Dr. Crowcroft was Chief Investigator of the Health Protection Agency Prospective Aetiological Study of Encephalitis (UK Department of Health funded) and led the project from its conception in 2005 to its end in 2009. The study refined our understanding of the epidemiology of encephalitis and improved detection of its causes. An important finding was that a cause can be identified for the majority of cases by implementing a standard microbiological diagnostic algorithm and by considering immune-mediated causes.
  • Influenza research in emergencies: In 2009 Dr. Crowcroft was the PI for a suite of pandemic influenza H1N1 studies funded by CIHR, PHAC, OAHPP, and Ministry of Health and Long Term Care (MOHLTC). This included an influenza sero-epidemiology study that led to an international partnership with a Consortium for the standardization of influenza sero-epidemiology.
  • In 2007-11 Dr. Crowcroft was the Ontario PI for an Influenza Vaccine Effectiveness study led by the British Columbia. Analysis of results from this network early in the 2009 pandemic of H1N1 influenza revealed a controversial finding that the 2008/9 seasonal influenza vaccine appeared to be associated with increased risk of acquiring the pandemic strain. Dr. Crowcroft worked with colleagues in BC and Quebec to rapidly design and implement three confirmatory studies, including a case control study in Ontario. The studies confirmed the finding, and attracted considerable interest including from the media and WHO.
  • Sero-epidemiology: a new field for Canada: Sero-epidemiology has not been as well established in Canada for assessing immunization programs as in other countries. In order to fill this gap, Dr. Crowcroft established a multi-disciplinary Canadian network of partners in public health, mathematical modelling and microbiology (Immunity of Canadians and Risk of Epidemics iCARE). This group held a CIHR-funded meeting in 2010. They have completed validation and calibration studies for measles and rubella, with varicella studies under development. Since June 2014, iCARE is now funded as part of CIRN.
  • Dr. Crowcroft is an associate editor at Eurosurveillance, an international board member Lancet Infectious Diseases and regular peer reviewer for other high impact journals including the Lancet, the British Medical Journal and the Canadian Medical Journal. She therefore contributes actively to the peer review infrastructure on which the quality of our scientific work and professional practice relies.
  • Since April 2015 Dr. Crowcroft has taken leadership in a new cross-organizational initiative in Applied Immunization Research at PHO.

Representative Publications

Top 5 publications

  1. Granerod J, Ambrose HE, Davies NW, Clewley JP, Walsh AL, Morgan D, Cunningham R, Zuckerman M, Mutton KJ, Solomon T, Ward KN, Lunn MP, Irani SR, Vincent A, Brown DW, Crowcroft NS; UK Health Protection Agency (HPA) Aetiology of Encephalitis Study Group. Causes of encephalitis and differences in their clinical presentations in England: a multicentre, population-based prospective study. Lancet Infect Dis. 2010 Dec;10(12):835-44. Impact factor 19.446, citations 242 on 4th August 2015. Senior responsible author.
  2. Deeks SL, Lim GH, Simpson MA, Gagné L, Gubbay J, Kristjanson E, Fung C, Crowcroft NS. An assessment of mumps vaccine effectiveness by dose during an outbreak in Canada. CMAJ. 2011 Jun 14;183(9):1014-20 Impact factor 6.0 citations 20 on 8th August 2015. Senior responsible author
  3. Skowronski DM, De Serres G, Crowcroft NS, Janjua NZ, Boulianne N, Hottes TS, Rosella LC, Dickinson JA, Gilca R, Sethi P, Ouhoummane N, Willison DJ, Rouleau I, Petric M, Fonseca K, Drews SJ, Rebbapragada A, Charest H, Hamelin ME, Boivin G, Gardy JL, Li Y, Kwindt TL, Patrick DM, Brunham RC, Canadian SAVOIR Team. Association between 2008-09 seasonal influenza vaccine and pandemic H1N1 illness during Spring-Summer 2009: four observational studies from Canada. PLoS Med. 2010 Apr 6;7(4):e1000258. (Impact factor 14.429, 135 citations by 4th August 2015). This paper combines findings from four studies. I am PI for the Ontario portion of the sentinel study component and PI for the Ontario Case control study that is included. I would therefore consider my contribution to be as a senior responsible author (Ontario).
  4.  Crowcroft NS, Thampi N. The prevention and management of rabies. BMJ. 2015 Jan 14;350:g7827. doi: 10.1136/bmj.g7827 (Impact factor 17.455, citations 2 by 4th August 2015) Principal Author
  5. Crowcroft NS, Deeks SL, Upshur RE. Do we need a new approach to making vaccine recommendations? BMJ. 2015 Jan 30. (Impact factor 17.445, No citations yet, but several comments posted online along with an authors’ response, included in CPA attachments) Available from: http://www.bmj.com/content/350/bmj.h308. Principal Author.

Recent Publications

  1. Savage R, Winter A, Rosella L, Olsha R, Gubbay J, Skowronski D, Crowcroft N. Strengths and Limitations of assessing influenza vaccine effectiveness using routinely collected, passive surveillance data in Ontario, Canada, 2007 to 2012: Balancing efficiency versus quality. Eurosurveillance. 2015 Apr 23;20(16). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=21100
  2. Thampi N, Gurol-Urganci I, Crowcroft NS, Sander B. Pertussis Post-Exposure Prophylaxis among Household Contacts: A Cost-Utility Analysis. PLoS One. 2015 Mar 6;10(3). Available from: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119271
  3. McCarthy J, Halperin S, Bettinger J, Langley J, Crowcroft N, Deeks S, Kwong J, De Serres G, Top K, McNeil S, Scheifele D. Canadian vaccine research networks: Vaccine safety resources for Canada. Can Commun Dis Rep. 2015 Feb 20;41(S-1):18-23. Available from: http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/15vol41/dr-rm41-04/assets/images/pdf-eng.png.
  4. Hashim A, Dang V, Bolotin S, Crowcroft NS. How and why researchers use the number needed to vaccinate to inform decision making – a systematic review. Vaccine. 2015 Feb 4;33(6):753-758. Available from: http://www.sciencedirect.com/science/article/pii/S0264410X14016867.
  5. Hawken S, Kwong JC, Deeks SL, Crowcroft NS, McGeer A, Ducharme R, Campitelli MA, Coyle D, Wilson K. Simulation Study of the Effect of Influenza and Influenza Vaccination on Risk of Acquiring Guillain-Barré Syndrome. Emerging Infect Dis. 2015 Feb;21(2). Available from: http://wwwnc.cdc.gov/eid/article/21/2/13-1879_article
  6. Crowcroft NS, Deeks SL, Upshur RE. Do we need a new approach to making vaccine recommendations? BMJ. 2015 Jan 30. Available from: http://www.bmj.com/content/350/bmj.h308.
  7. Crowcroft NS, Nisha T. Clinical Review: The prevention and management of rabies. BMJ. 2015 Jan 14;350
  8. Durrheim DN, Crowcroft NS, Strebel PM. Measles – The epidemiology of elimination. Vaccine. 2014 Nov 4;32(51):6880-6883. Available from: http://www.sciencedirect.com/science/article/pii/S0264410X14014510.
  9. Tu HA, Deeks SL, Morris SK, Strifler L, Crowcroft NS, Jamieson FB, Kwong JC, Coyte PC, Krahn M, Sander B. Economic evaluation of meningococcal serogroup B childhood vaccination in Ontario, Canada. Vaccine. 2014 Sep 22;32(42):5436-5446.
  10. Middleton D, Johnson K, Rosatte R, Hobbs L, Moore S, Rosella L, Crowcroft N. Human Rabies Post-Exposure Prophylaxis and Animal Rabies in Ontario, Canada, 2001-2012. Zoonoses and Public Health. 2014 Sep 22. Available from: http://onlinelibrary.wiley.com/doi/10.1111/zph.12155/abstract;jsessionid=538247034260FCCDAFA890CB7833C47E.f01t02.
  11.  Harris T, Wong K, Stanford L, Fediurek J, Crowcroft NS, Deeks SL. Did narcolepsy occur following administration of AS03-adjuvanted A(H1N1) pandemic vaccine in Ontario, Canada? A review of post-marketing safety surveillance data. Eurosurveillance. 2014 Sep 11;19(36). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20900.
  12. Ramanuj PP, Granerød J, Davies NWS, Conti S, Brown DWG, Crowcroft NS. Quality of Life and Associated Socio-Clinical Factors afterEncephalitis in Children and Adults in England: A Population-Based, Prospective Cohort Study. Plos ONE. 2014 Jul 29. Available from: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0103496.
  13. Middleton D, Savage R, Tighe M, Vrbova L, Walton R, Whitfield Y, Varga C, Lee B, Rosella L, Dhar B, Johnson C, Ahmed R, Allen V, Crowcroft N. Risk factors for sporadic domestically acquired Salmonella serovar Enteritidis infections: a case-control study in Ontario, Canada, 2011. Epidemiol Infect. 2014 Jul;142(7):1411-21.