11 General Introduction 1 and makes findings more easily generalisable. Second, even though randomised controlled trials are ideal to answer causal questions, this is not always ethical or feasible (for example due to the amount of time, money or patients needed). However, large, observational datasets, under some conditions, can be used to answer causal questions9. Third, since many of these datasets contain routinely collected data, typically little effort is involved for researches to use the data. New developments make mining of data from EHR possible, and several commercial companies use anonymised health care data, for example from healthcare insurance declarations. Fourth, large datasets allow the identification of patterns or subgroups that cannot be identified in smaller datasets. Finally, by reducing the manual data collection burden, researchers can expedite the pace of research discoveries and potentially improve patient care. The idea to use this data to improve care is not new11,12. International Classification of Diseases (ICD) codes are a common way to study EHR data4. Like many other areas of medicine, the field of infectious diseases (ID) saw a large increase in the number of publications using big data7,13. A common use of these new and large datasets are for infectious diseasesurveillance7 (discussed below), but has also been used in other aspects of infectious disease research, such as improvement of care4. Viral respiratory disease Outbreaks of seasonal and pandemic viruses have shaped recent human history. From the “Spanish Flu” in 1918 to the recent Severe Acute Respiratory Syndrome Coronavirus -2 (SARS-CoV-2) pandemic that started in 2019, these respiratory viruses have had a massive global impact. With the increased possibility for travel for many people, and the close proximity of animals to humans, the likelihood of the emergence of a new variant with pandemic potential increases14. As in many developed countries intensive care units (ICUs) and hospitals operate close to capacity, this means that outbreaks of seasonal or pandemic viruses can rapidly lead to serious capacity problems14–17. Shortages of beds15, ventilators18 and medication19 have been reported during previous (seasonal or pandemic) outbreaks of viral respiratory disease14,16. An epidemic is defined as an outbreak that spreads over a large geographical area, whereas a pandemic is defined as an epidemic that spreads globally20. The 19181919 “Spanish Flu” (influenza) is the deadliest pandemic in recorded history, during which an estimated 50-100 million people died, over 2.5% of the world population at the time14,21. Since 1918, there have been several influenza virus pandemics (1957, 1968 and 2009)22,23. Both the 1957 and 1968 influenza pandemics resulted in an estimated one to two million deaths24. Before the recent coronavirus pandemic caused by SARS-CoV-2, in 2003 the SARS-1 pandemic resulted in over 8000 infections and almost 800 deaths in 27 countries25,26. No human cases of SARS-1
RkJQdWJsaXNoZXIy MTk4NDMw