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Hannah Williams

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Hannah Williams

Hannah Williams

SSI fellow

UK Health Security Agency

UK Health Security Agency


  • Infectious disease modelling
  • Outreach and engagement
  • Learning things, whether it’s work related or hobbies
  • Looking after other people’s dogs (or friendly cats)

My work

In my role as a mathematical modeller at Public Health England, I provide scientific advice to government departments and healthcare providers about the COVID-19 pandemic and wider disease threats. Much of my work supports the planning of guidance, often when there is little data available. For example, early on in the COVID-19 outbreak, I helped to estimate the number of cases that could be found on a cruise ship under quarantine, and the potential number of imported cases that might be seen when UK citizens were repatriated. This work was also developed to support infection control management in other settings, such as adult social care and the prison services. Another big piece of work has been assessing the public health value of different self-isolation and testing regimes, especially when lateral flow devices were emerging as a more accessible way to test the wider population.

I work with a team that has membership from across PHE, other government agencies, and universities. We have to work quickly due to the evolving nature of the pandemic and the necessity for decisions to be guided by evidence. This is a challenging environment when writing code, since there is often not the luxury of time to carry out the standard review processes. This has led me to more fully consider the trade-off between code development and the requirement for immediate results. This has given me a greater appreciation of the need to develop good practice in non-response times so that it is second nature during a response.

I mostly use Python, but also a bit of R, and regularly make use of our high-performance computers to improve run-times for the larger scenario simulations. During the fellowship I plan to attend conferences and learn best practices from other sectors regarding software sustainability. I believe in investing in colleagues and developing the wider team, which ultimately improves the quality of collaboration and team resilience. To this end, I will organise seminars within my organisation to share different ideas, and encourage an environment where we can learn, develop and support together.

Online Presence

My institutional website


Check out contributions by and mentions of Hannah Williams on www.software.ac.uk