Epidemiology: the science of prevention

Public Health, epidemiology and prevention have been in the headlines since the start of the Covid-19 health crisis. We take a look at these topics with Christophe Tzourio, Professor of Epidemiology at the University of Bordeaux and Director of the Bordeaux Population Health research center (BPH – Inserm and University of Bordeaux) and the Student Health Center of the University of Bordeaux.

  • 06/11/2020

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What exactly is epidemiology? In what ways is this discipline essential?

Epidemiology is a crucial component of public health. In its first, literal sense, it is a science that studies epidemics, the way infections are spread and how to tackle them. This means identifying cases and transmission of a disease and modeling its spread in order to control epidemics. However, epidemiology also involves another component that is less well known to the general public: the analysis of population health. We, the epidemiologists, seek to identify the key factors involved in diseases, sometimes referred to as risk factors, their distribution and their impact, as well as the profiles of groups at high risk of disease within the population. This identification enables the development of targeted prevention and treatment strategies and, more generally, a better understanding of disease mechanisms.

Our work involves carrying out surveys, often following cohorts of people for several years. For example, it was a large-scale English epidemiological study carried out in the 1950s that demonstrated the link between smoking and lung cancer. In the same way, numerous strokes are now avoided because epidemiological studies have identified the underlying causes and risk factors and preventive actions may be implemented. In this way, epidemiology can provide answers to major health problems on a community level.

What are the possible responses to address the Covid-19 epidemic?

With the emergence of Covid-19, epidemiologists from the Bordeaux Population Health research center (BPH - Inserm and the University of Bordeaux) have been hard at work on the epidemic and its impact. We launched 36 research projects on the subject during the spring 2020 lockdown, at a time when working conditions were difficult. Like others, we felt that it was essential to provide knowledge in order to understand and control the epidemic and its consequences as quickly as possible.

For my part, I have been conducting research on student health for the past ten years (the i-Share study with over 21,000 participants). My team and I decided to examine the impact of lockdown on the mental health of this already very vulnerable population. During the spring, we launched a large-scale study, called Confins. While our knowledge of the infectious and immune aspects of Covid-19 is increasing, there is less appreciation of the psychological effects of the situation, which could be serious and long-term for many. There are multiple causes for this psychological impact among students: fear of the disease for themselves and, especially, for their older relatives; the direct economic consequences – many students were unable to have part-time or seasonal jobs during lockdown and over the summer; disruption of classes and exams, as well as the social isolation. The aim of this cohort study is to identify the profile of those people who could become overwhelmed by the situation, become severely depressed or drop out of the education system. Its ultimate purpose is to develop tools for immediate support and prevention and to encourage those seriously effected to seek help. 

What do the first results of the Confins study reveal?

We recruited students and non-students (3,500 participants in total) with very comparable characteristics apart from their status and age. As we feared, mental health indicators are much worse among students. For example, high levels of stress, anxiety or depression are almost twice as common among students as among non-students, a substantial difference. It also affects self-confidence, with 32% of students seeing themselves as losers compared to 16% of non-students. Finally, 11% of students admit to having had suicidal thoughts during lockdown. This study demonstrates the frequency of psychological vulnerability among this student population and the impact of lockdown. It provides figures alerting decision-makers to the need for reinforced support strategies. It also makes it possible to identify risk profiles and design prevention strategies oriented more specifically at this target. Prevention, an aspect that is often neglected in the French healthcare system, has an important role to play in these mental health issues and in this population of young adults in order to limit the impact of the current crisis and enable them to manage it as well as possible.

What lessons do you draw from this health crisis?

Overall, I think that French people have resisted well, including young people, who are more worried about the situation than some media or political figures suggest. It is true that young adults are more exposed because of their multiple social interactions, and especially if they do not apply all the relevant protective measures. Just like everyone else, they need to make an effort to limit the risks of contamination, especially now, when the epidemic is worsening. At university, the students are following the advice and instructions remarkably well and adapting to these difficult circumstances. The results of the Confins study show that they are also very concerned about the impact of the virus on their loved ones and that their level of altruism cannot be questioned.

There are many uncertainties about this epidemic, but it is unlikely to come to an end soon, with or without a vaccination. I am concerned about our ability to adapt to living with the personal and collective upheavals induced by the crisis in the long term. The mental health effects are already being felt and their burden is likely to increase. With future epidemics more than likely, it is all the more important to study them and develop prevention strategies. It is a matter of urgency.