In the midst of a global pandemic, we have seen many countries implement different measures to try to eradicate the virus. As we learned in lecture and as discussed in the article, viruses spread through social networks and can spread easily through strongly connected components. As a result, the article “A network-based explanation of why most COVID-19 infection curves are linear” by Turner, Klimek, and Hanel intrigued me because it was a network-based explanation for the spread of COVID-19 as well as a network-based explanation for prevention measures.
The first measure that we have all heard is a lockdown as seen in early March in Ontario. Turner et al suggest that in order for a person to become infected with the virus they must satisfy two criteria as seen below:
- There is a social interaction between an infected and a susceptible person and
- This contact is intense enough to lead to disease transmission.
Assuming a realistic contact network with degree 5, there is an average of 7.2 critical contacts per person. With lockdown measures, this reduces the number of critical contacts of each person to 2.5 people. Essentially, given a social network where nodes are people and edges are intense contact as defined above, a lockdown removes many edges hence limiting the ease of spread throughout the network.
Here we can see the results of the US, who did not implement lockdowns during the given timeframe and Austria, who did. We can conclude that bringing the number of critical contacts down to a household amount like 2.5 can dramatically change the course of the pandemic.
Now after the first wave, many places began to ease up on restrictions. Places like Ontario began to reopen businesses and lifted much of the lockdown as numbers began to drop. To prevent cases from flaring up again, another measure known as “Social Distancing” was implemented.
As discussed by Turner et al, social distancing is another way of removing those edges between nodes hence creating a more sparse network. Even though more people were seeing each other, social distancing should limit the spread because those interactions would not satisfy criteria 2 as defined above. However, we know that humans are social beings and the longing for meaningful social interactions was immense after months of lockdown. Holidays, birthdays, and other events eventually caused a lot of those edges to appear again, creating more strongly connected components hence we have entered the second phase of this pandemic.
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