A study analyzing the link between the movement of people and the spread of the coronavirus reveals three groups of countries

A new study analyzing the link between reduced movement of people and the spread of the coronavirus in 2020 shows that in some countries the virus spread faster when people stayed at home. Moreover, restricting people’s mobility to some extent has been shown, in retrospect, to be more effective in minimizing the spread of SARS-CoV-2 than extreme mobility restrictions, in many countries.

“More than two years mark the beginning of the pandemic which has changed the lives of many of us in various ways. The current development of the spread of SARS-CoV-2 suggests that this chapter of history titled COVID-19 could hopefully fade for However, there is still much to learn about this. Reflecting on how we have responded to the pandemic could help us learn useful lessons on how to minimize the damage of challenges similar ones, especially now that infectious diseases seem to be a re-emerging threat,” underline researchers Mounir Ould Setti and Sylvain Tollis.

Government-imposed lockdowns and movement restrictions have probably been the hallmark of the response to this pandemic. These interventions have been found to be invasive in certain circumstances and settings. Have lockdowns and movement restrictions been effective in reducing the spread of SARS-CoV-2? Researchers from the University of Eastern Finland analyzed how the movement of people aligned with daily changes in the effective replication number of SARS-CoV-2. The effective replication number reflects the rate of disease spread as it captures the dynamic changes in viral transmission from person to person. Mobility metrics are based on anonymized location data from users of Google services who have location history enabled on their mobile phones. Positions are classified into different mobility categories, including, for example, residential mobility, which indicates that people stay at home. The researchers focused on the pre-vaccination and worrying pre-variants phase of the pandemic from February 15 to December 31, 2020 by analyzing daily changes in mobility and the spread of SARS-CoV-2 in 125 countries and 52 regions. or states of the United States. .

The analysis identified three groups of countries based on patterns of correlations between mobility indicators and the effective reproduction number of SARS-CoV-2. Group 1 was composed of countries with “normal” correlations, i.e. negative correlations between residential mobility and the spread of SARS-CoV-2, for example the United States, Turkey and most countries of the OECD. Group 2 included countries with “reverse” correlations, referring to positive correlations between residential mobility and the spread of SARS-CoV-2. Group 3 consisted of countries with more complex correlation patterns or “inconclusive” correlations.

In group 1 countries like Austria, the more time people spend at home, the less the spread of the disease is recorded, while in group 2 countries like Bolivia, the exact opposite is observed: the more time people spend at home, the greater the disease. diffusion. In addition, in many countries, correlation patterns between mobility and disease spread showed minimal disease spread at an intermediate level of mobility restriction (‘U’ correlations), indicating an optimal level. above which restricting people’s mobility could lead to more spread of the disease. In other words, full lockdowns could have been counterproductive at some levels and in some countries.

The authors concluded that a systematic analysis of correlations between mobility and disease spread at the regional level could help understand the optimal level of mobility restriction that minimizes the spread of SARS-CoV-2 in that specific region.