What is your expertise and how did you come to fight against COVID-19?

I have been working at the Epidemiology and Microbial Genomics Service of the LNS’s Microbiology Department since 2016, first as a PhD student, and currently as a postdoctoral researcher. Before moving to Luxembourg, I studied in Georgia, Belgium and the Netherlands, specializing in genetic epidemiology and health sciences. Additionally, I gained practical experience in a hospital in Georgia. My fight against COVID-19 is closely linked to a comprehensive study on social contacts within the population of Luxembourg during and after the COVID-19 lockdown.

What is the aim of this study?

The study is based on a series of online surveys. The aim of these surveys was to provide an evidence-based quantitative assessment of how government measures have impacted social contacts in the country – and how this could potentially affect the spread of the virus. Four surveys were therefore run during the period of the lockdown itself and three more took place between June and August. The latter were used to understand how social behaviour would change after relaxing or lifting measures.

What was your role in this study?

I shared this mission with my Epidemiology and Microbial Genomics Service colleagues Joël Mossong and Malte Herold, as well as Jean-Paul Bertemes from the Fonds National de la Recherche (FNR). My tasks included data curation, formal analysis, methodology, visualization and the set-up of the project report.

How did you cooperate with other institutions?

The project was conducted in very close cooperation with the FNR. They supported us with the data collection and questionnaires, using their science.lu website when it came to calling on the population to participate in online surveys.

What was the most important challenge that you had to face during the study?

A key challenge was the timeframe: the first stage of the surveys started on 25 March, and thus only one week after the state of emergency began. This meant  that we had to develop a survey design in a very short amount of time, which was achieved thanks to Joël Mossong and Jean-Paul Bertemes. To ensure a high level of participation, the surveys were purposely designed to have only a small number of questions.

How was the study designed in the end?

The questionnaire was modified according to the government recommendations in place: during the lockdown, we collected age category, number of individuals living in the household, number of contacts within the last 24 hours, nationality and the location where most contacts had occurred. The post-lockdown survey included additional questions to identify the number of contacts that had taken place without a facemask being worn.

What were the key findings of the study?

Our study suggests that the strict physical distancing measures implemented in Luxembourg during the lockdown resulted in a more than 80% reduction of the average number of contacts per day compared to the pre-pandemic period. This would explain the decline in the SARS-CoV-2 transmission rate, resulting in turn in the rapid decline of COVID-19 cases observed during the lockdown. After the lockdown was lifted, the average number of contacts increased, although it remained 60% lower than before the pandemic. An additional survey, which was run in August, showed a slight decrease in social contacts. Furthermore, our results suggest that older individuals are more compliant with restriction measures compared to younger persons, which is expected since the risk of hospitalization and death from COVID-19 increases with age.

Link to the study: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237128