London School of Hygiene & Tropical Medicine

Khitam Muhsen is a professor of Epidemiology and Preventive Medicine at the School of Public Health, Tel Aviv University, Israel. She has been on a sabbatical as a visiting fellow at LSHTM since December 2022, working with Prof. Elizabeth Miller and colleagues at the Vaccine Centre.

Tell us about your current research

My main research field is the epidemiology of infectious diseases and vaccines, focusing on enteric infections, Helicobacter pylori infection and vaccine-preventable diseases. During the COVID-19 pandemic, I became involved in several observational studies in Israel, in which we assessed disparities in the disease burden, the effectiveness of COVID-19 vaccines and COVID-19 vaccine hesitancy.

During my sabbatical, I have been working on several research projects with Prof. Miller and the UKHSA faculty members and team. The main project is on the associations between COVID-19 vaccination and the risk of infection among household contacts of confirmed cases in England. This prospective study was conducted between February 2021 and February 2022, thus capturing various periods of the Alpha, Delta and Omicron variants and evolving knowledge about these variants and COVID-19 vaccines that shaped COVID-19 vaccination policy. The study participants were provided with nasal swabs collected at enrolment, 3 and 7 days after that and tested for SARS-CoV-2. We found that nearly half of the adult contacts tested positive for SARS-CoV-2 during the follow-up, which suggests intense transmission within households, much higher than studies that utilised databases or electronic health records. We also found that if the contacts had an up-to-date COVID-19 vaccination, their risk of the infection was lower than unvaccinated contacts, with the highest protection found among contacts who received 3 doses. The protection induced by COVID-19 vaccination was evident during the Alpha and Delta waves, but it was substantially reduced during Omicron and evident only for those who received booster vaccination. Moreover, additional protection was attained if the index cases were also vaccinated.  

How did you first become interested in vaccines?

I started my career as a public health and paediatric nurse in Israel, which was a significant baseline experience that provided me with the 'clinical' perspective of public health. While working as a nurse, I was taken aback by the relatively high infant mortality in the Arab population. Therefore, I decided to study epidemiology and preventive medicine to understand the distribution of diseases and risk factors and plan and implement interventions to improve health and prevent illness, disability, and premature death. I 'fell in love' with epidemiology and established a new career in this field.

My studies with Prof. Liz Miller at LSHTM are a natural trajectory over my studies in Israel on COVID-19 and vaccine-preventable diseases. I was fortunate to work closely with Prof. Miller and the UKHSA investigators on these studies and learn new methods and the UK public health experience with COVID-19 and other infectious diseases.

What do you find particularly interesting working as a member of the Vaccine Centre?

During my sabbatical, I have served as a member of the steering committee of the School's Vaccine Centre. This was a wonderful experience demonstrating the cross-border collaboration, working with colleagues based in London, Uganda, and other countries. Additionally, the partnership between the Vaccine Centre and UKHSA is outstanding, serving as a successful model for collaborative work between academia and real-life public health practice.  

The Vaccine Centre plays a remarkable educational role in vaccines, reflected by organising multiple rich and multidisciplinary seminars and workshops dealing with the most current issues in vaccines and public health. Notably, the centre team was very welcoming and supportive during my stay, and I am very thankful for this wonderful and fruitful experience and friendship.

Where do you think your research will take you next?

My sabbatical at the LSHTM ends on 30 September 2023; by the same time, I start a new position as the head of the Department of Epidemiology and Preventive Medicine at the School of Public Health at Tel Aviv University. I plan to continue and strengthen the collaboration with LSHTM researchers that successfully developed over the past few months and expand our collaboration in both research and teaching.

What are some of the real-life implications of your work?

My studies can support vaccine policymaking, identify susceptible populations at risk for infectious diseases, plan interventions to improve health and reduce the burden of infectious diseases.

What do you like doing in your spare time?

I enjoy jogging, walking in the parks, reading books and visiting museums.   

How can people get and stay in touch with you?

Email: kmuhsen@tauex.tau.ac.il