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DR Joris Hemelaar

DR Joris Hemelaar


I obtained my BSc and MSc (cum laude) in Molecular Biology and Genetics at Leiden University, The Netherlands (1997). I went on to complete a DPhil in Molecular Immunology with Prof Sir Andrew McMichael FRS at the Weatherall Institute of Molecular Medicine and Trinity College, Oxford (2001). This was followed by post-doctoral research with Prof Hidde Ploegh at the Harvard Medical School, Boston, USA.

I went on to complete my BM BCh medical degree at Magdalen College, Oxford (2007) and, after working as a Foundation Doctor in London for two years, I returned to Oxford in 2009 to commence my Specialty Training in Obstetrics and Gynaecology as an Academic Clinical Fellow at the John Radcliffe Hospital.

In 2012 I was appointed as a Clinical Lecturer in the Nuffield Department of Women's & Reproductive Health, and in 2015 I was awarded the Sir Paul Nurse Junior Research Fellowship at Linacre College, Oxford. I also hold an honorary Senior Researcher position at the University of the Witwatersrand, Johannesburg, South Africa.


  • 2014 Award for most highly cited article in AIDS journal
  • 2013 Membership of the Royal College of Obstetricians and Gynaecologists, London.
  • 2012 Diploma in Evidence-Based Medicine, University of Oxford
  • 2009 - 2012 Academic Clinical Fellowship (NIHR)
  • 2005 - 2007 Foulkes Foundation Fellowship.
  • 1998 - 2001 Medical Research Council PhD Fellowship.
  • 1997 Talent Scholarship, Minister of Education, The Netherlands.

Research groups

Joris Hemelaar

BM BCh (Oxon) BSc (Hons) MSc (Hons) PGDip DPhil (Oxon) MRCOG

Clinical Lecturer

  • Principal Investigator
  • Sir Paul Nurse Junior Research Fellow, Linacre College, Oxford.
  • Specialty Registrar, Obstetrics & Gynaecology, John Radcliffe Hospital, Oxford.
  • Senior Researcher, Wits University, South Africa.
  • Consultant, HIV Vaccine Initiative, WHO/UNAIDS, Geneva.


Maternal HIV infection and antiretroviral treatment and adverse pregnancy outcomes.

Maternal HIV infection not only poses a risk of transmission of HIV to the baby, but we have shown that it is also associated with increased rates of adverse pregnancy outcomes, such as preterm birth (PTB), low birth weight (LBW), small for gestational age (SGA), and stillbirth (SB). The HIV pandemic continues to grow, with 36.7 million people currently infected, of whom 7.1 million reside in South Africa. 92 percent of HIV-infected pregnant women live in sub-Saharan Africa. Preterm birth and low birth weight are the leading causes of perinatal morbidity and mortality around the world.

Our aims are to accurately estimate the burden of adverse pregnancy outcomes associated with maternal HIV infection and antiretroviral treatment, and to elucidate the mechanisms underlying these pathologies with a view to developing targeted, predictive, preventative and interventional strategies.

To investigate the associations of maternal HIV infection and antiretroviral treatment with a range of adverse pregnancy outcomes we are conducting a number of systematic literature reviews and (network) meta-analyses.

We are also conducting a large-scale prospective pregnancy cohort study in Chris Hani Baragwanath Hospital, Soweto, South Africa, located in an area with a very high HIV prevalence (30%). We closely follow HIV-positive and HIV-negative women throughout pregnancy, which will give us a better understanding of the relationship between maternal HIV infection, antiretroviral therapy and adverse pregnancy outcomes.

Within the same cohort, and as an adjunct to INTERBIO-21st, we collected biological samples (blood and placenta) which we use to characterise the immune responses associated with HIV infection in pregnancy by which HIV may cause PTB and SGA. A better understanding of these mechanisms should pave the way to the development of specific predictive, preventative and interventional strategies applicable in the developing world.

Global molecular epidemiology of HIV.

HIV-1 genetic variability plays a central role in the HIV pandemic. Multiple zoonotic transmissions of SIV to humans have resulted in distinct HIV lineages in humans which have further diversified within the population over time. High rates of mutation and recombination during HIV reverse transcription create a genetic diversity in the host which is subject to selection pressures by the immune response and antiretroviral treatment. As a result, the global distribution of HIV-1 subtypes and recombinants is extremely complex and dynamic. The increasing diversity has profound implications for many aspects of the pandemic, including viral pathogenicity, transmission, diagnosis, treatment, and vaccine development.

HIV-1 genetic diversity surveillance is therefore crucial in tackling the pandemic and in collaboration with the HIV Vaccine Initiative at the World Health Organization, Geneva, we collect HIV molecular epidemiology data from around the world. We use this data to describe the distribution and trends in national, regional, and global HIV genetic diversity, information which is essential for HIV vaccine development.

We also use this information to estimate the need for subtype-specific HIV vaccines nationally, regionally and globally.

We further link our HIV distribution data to regional and global transport and accessibility models to investigate the role of infrastructure and human migration in the spread of HIV.


  • Dr Wahyu Santosa, (DPhil Student, Hertford College)
  • Christine Shi (Clinical medical student)
  • Krithi Ravi (Clinical medical student)
  • Harriet Sexton (FHS student, Queen’s College)
  • Shanghavie Loganathan (FHS student, Christ Church College)


  • Isabella Fleminger
  • Dr Chrystelle (Opope) Wedi
  • Dr Ramyia Elangovan
  • Jason Yun
  • Susan Honeyman
  • Charlotte Nesbitt
  • Leslie Dickson-Tetteh
  • Sierra Weingartner
  • Dr Ruth Corrigan
  • Dr Sarah Montgomery-Taylor 
  • Dr Christina Chan (Research Assistant)
  • Zoe Brandon (FHS student, St Anne’s College)
  • Mary Kumarendran (FHS student, Exeter College)
  • Michael Jenks (FHS student, Queen’s College)


  • Prof Stephen Kennedy, NDWRH, Oxford
  • Prof Shane Norris, DPHRU, University of the Witwatersrand, South Africa
  • Prof Philip Goulder, Peter Medawar Building for Pathogen Research, Oxford
  • Dr Peter Ghys, UNAIDS, Geneva, Switzerland
  • Dr Andy Tatem, University of Southampton, UK


Direct Entry Research Degrees