Imperial College London


Faculty of MedicineSchool of Public Health

Prof of Infectious Disease & Vaccine Epidemiology



+44 (0)20 7594 3264n.grassly Website




G36Medical SchoolSt Mary's Campus






I am an epidemiologist and biologist with a particular interest in vaccines and intestinal infections. I head the Vaccine Epidemiology research group within the Department of Infectious Disease Epidemiology at Imperial College London.

Over the last decade I have worked extensively on poliovirus, identifying failure of the oral vaccine in India as a major challenge to global eradication. This work has led to clinical trials that aim to improve mucosal immunity and limit vaccine failure, which I am currently pursuing in collaboration with colleagues at the Christian Medical College in Vellore (where I am an adjunct faculty member). 

A major focus of our current research is to understand and improve the response to live oral vaccines, which are poorly immunogenic when given to children in low-income countries. Through clinical trials and new technologies including immunophenotyping arrays and next generation sequencing we are uncovering the relationship between the intestinal microbiota, immune function and response to vaccination.

We also work closely with the Global Polio Eradication Initiative as a collaborating institute on data analysis and modelling. We provide evidence from epidemiological studies, clinical trials and analysis of surveillance data to support decision making by the Initiative. We have estimated the effectiveness of new monovalent and bivalent vaccines, the impact of novel strategies for vaccine delivery and role of different populations and age-groups in poliovirus transmission. 

For more details of the current research interests of my group, please click on the link above.

I supervise a number of PhD students working on infectious diseases and vaccine epidemiology. If you are interested in joining our group please email me.

You can also follow us on Twitter @VaccineEpi.

Selected recent publications

Pons-Salort M, Burns CC, Lyons H, Blake IM, Jafari H, Oberste MS, Kew, OM and Grassly NC 2016. Preventing vaccine-derived poliovirus emergence during the polio endgame. PLoS Pathog, 12(7), e1005728 [full text]

Grassly NC et al. 2016 The effect of azithromycin on the immunogenicity of oral poliovirus vaccine: a double-blind randomised placebo-controlled trial in seronegative Indian infants. Lancet Infect Dis 16:905-914. [abstract]

Blake IM, Chenoweth P, Okayasu H, Donnelly CA, Aylward RB & Grassly NC. 2016 Faster detection of poliomyelitis outbreaks to support polio eradication. Emerg Infect Dis 22: 449-456. [full text]

Grassly NC, Kang G and Kampmann B (2015) Biological challenges to effective vaccines in the developing world. Phil Trans Roy Soc B 370 (1671) [full text]

Jafari H, Deshpande JM, Sutter RW, Bahl S, Verma H, Ahmad M, Kunwar A, Vishwakarma R, Agarwal A, Jain S, Estivariz C,Sethi R, Molodecky NA, Grassly NC, Pallansch MA, Chatterjee A, Aylward RB (2014) Efficacy of inactivated poliovirus vaccine in India. Science 345:922-925 [abstract]

John J, Giri S, Karthikeyan AS, Iturriza-Gomara M, Muliyil JP, Abraham A, Grassly NC* and Kang G* (2014) Effect of a single inactivated poliovirus vaccine dose on intestinal immunity against poliovirus in children previously given oral vaccine: an open-label, randomised controlled trial. Lancet 384:1505-1512 [abstract]. ,*joint first,senior authors

Blake IM, Martin R, Goel A, Khetsuriani N, Everts J, Wolff C, Wassilak S, Aylward RB and Grassly NC (2014) The role of older children and adults in wild poliovirus transmission Proc Natl Acad Sci USA Vol:111:10604-10609 [full text]



O'Reilly KM, grassly, molodecky, An assessment of the geographical risks of wild and vaccine-derived poliomyelitis outbreaks in Africa and Asia., Bmc Infectious Diseases, ISSN:1471-2334

John J, Giri S, Karthikeyan AS, et al., 2017, The Duration of Intestinal Immunity After an Inactivated Poliovirus Vaccine Booster Dose in Children Immunized With Oral Vaccine: A Randomized Controlled Trial, Journal of Infectious Diseases, Vol:215, ISSN:0022-1899, Pages:529-536

Shirreff G, Wadood MZ, Vaz RG, et al., 2017, Estimated Effect of Inactivated Poliovirus Vaccine Campaigns, Nigeria and Pakistan, January 2014-April 2016, Emerging Infectious Diseases, Vol:23, ISSN:1080-6040, Pages:258-263

Blake IM, Chenoweth P, Okayasu H, et al., 2016, Faster Detection of Poliomyelitis Outbreaks to Support Polio Eradication, Emerging Infectious Diseases, Vol:22, ISSN:1080-6040, Pages:449-456

Grassly NC, Praharaj I, Babji S, et al., 2016, The effect of azithromycin on the immunogenicity of oral poliovirus vaccine: a double-blind randomised placebo-controlled trial in seronegative Indian infants, Lancet Infectious Diseases, Vol:16, ISSN:1473-3099, Pages:905-914

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