Understanding the spread and distribution of COVID-19 infection

What is it about?

During the early phases of the COVID-19 pandemic, the number of cases reported in different parts of the world varied widely. People saw a small number of cases in their locality even when many people were infected worldwide. But why did this happen? This study examines the reason behind this peculiar observation. The authors analyzed the reported cases of COVID-19 from March 2020, when the pandemic was in its early stages. They found that the pattern of infection cases and deaths followed a power law. This is a pattern where one quantity changes as a power of another. The observed pattern was the result of two processes at different scales. One involved a spread of the virus in different countries. The other was the accumulation of cases within each country. The authors further tested their theory with numerical simulations. The power law behavior thus explained why there were more infections in certain locations compared to others. In fact, the power law appears naturally from the spreading process. The authors, however, warn that this pattern may not be observed in a second wave outbreak.

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Photo by Martin Sanchez on Unsplash

Photo by Martin Sanchez on Unsplash

Why is it important?

Understanding how a disease spreads is crucial for setting up pandemic control measures. This study explains an important feature of the COVID-19 pandemic based on its spreading process alone. Although the explanation may only be true in the early stages, it suggests a universal rule for pandemic outbreaks. KEY TAKEAWAY: At the early stages of the pandemic, most COVID-19 cases occurred inside some specific countries. At the same time, other countries saw fewer cases. The same pattern was found at even smaller scales within countries. The reason has to do with the spreading process itself, which causes a power law pattern in the reported cases.