Esther van Kleef is a senior epidemiologist at the Institute of Tropical Medicine, Antwerp and holds a PhD in infectious disease epidemiology from the London School of Hygiene & Tropical Medicine. During her work experiences at national public health institutes (PHE, RIVM) and Oxford university, she has developed a keen interest in understanding the transmission-dynamics of pathogens and effectiveness of interventions, having largely focused on (modelling) antimicrobial resistance. Within the MOOD Project, Esther is working, together with MOOD partners, on identifying how to improve the integration of the threat of disease X in existing procedures of epidemic intelligence. She has supported analyses on ECDC mortality data related to different countries' Covid-19 measures in the context of MOOD's focus on early detection, preparedness, and monitoring of infectious diseases. She was recently selected among other scientists to join the Technical Advisory Group (TAG) created by WHO and UN DESA. The objective of the TAG is to obtain more accurate data on Covid-19 mortality cases, to help review WHO’s current methods, to come up with more reliable analytical methods, and to standardise the existing methods for surveillance data. Esther illustrates the effects of physical distancing and school reopening on cases reporting and age-specific SARS-CoV-2 transmission patterns, as discussed in the recently-published paper she co-authored (https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.7.2100065). For this study, the group of researchers employed operational data from the COVID-19 contact tracing system of the Brussels region and case reports made available via the Belgian institute for health, Sciensano.