Pandemics And Six Degrees Of Separation
A Social network analysis of the spread of COVID-19 and lessons from South Korea
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Stanley Milgram was a Professor in Harvard who did an interesting experiment. Milgram chose a stockbroker in Boston and then he contacted 296 volunteers, one third of them whom were from Boston and rest from Omaha, Nebraska more than 1400 Kilometers away. Each of the 296 volunteers received a booklet that they were supposed to send to the stockbroker in Boston. If they knew the stockbroker, they could send him directly and if they did not, they were asked to send to someone whom they thought could pass on to the stockbroker in Boston. Soon 64 of these booklets reached their destination and the average chain of connections it took was 5.2. This is how the concept six degrees of separation or the expression “it's a small world” came into our vocabulary.
In today’s world we know that it is not even six degrees of separation considering the global trade and travel and it is indeed a small world. This makes the spread of epidemics like Corona virus faster.
South Korea did a very good job of mapping the people affected by virus using technology and by Feb. 17, South Korea’s tally of COVID-19 patients was just 30 with zero deaths. The country thought the situation was well under control. Remember India now has more than 80 cases of people who have tested positive.
The 31st case in South Korea, patient No. 31, discovered on Feb. 18, was a member of a quasi-Christian cult called Shincheonji, one of the religious movements in the country. Within eight days of patient 31 contracting the virus, the count of infected people went up to 977. This cult is estimated to have approximately 240,000 followers. So, the 31st patient became the tipping point in spreading the virus widely across South Korea. Just one person managed to take the total number of people affected from just 30 to almost 1000. To understand this crazy spread, we need to look into the construct of social networks and roles different people play in social networks.
Role of Social Networks
While we know that the COVID-19 virus spreads through physical proximity and contact, would there be certain kinds of people who are more prone to getting the disease than others? I am not talking about the available data on elders and children who are more prone to the virus. I am talking about the social networks and our position in the networks that might have an impact on how prone we are to epidemics like this.
We are social animals and we have our social networks. These could be our friends, family, work colleagues, neighbours, etc. Some of us have more of a social life than others - more friends and more social interactions and depending on where we are in a social network, we have access to certain other members. In the diagram below each members are the nodes and the lines represents their relationships and connections. You can see that Faiz is more connected to others than Krunal.
Chances are that in an epidemic like COVID-19, Faiz could pass the virus to more people than Naina. At the same time if you want to pass a positive message to the community, Faiz will be in a better position than Naina.
In social network analysis Faiz is called a Hub and during an infectious disease outbreak could become a super spreader. There is a concept called centrality in Network Analysis and there are degrees of centrality - ‘betweenness centrality’ and ‘closeness centrality’. In layman’s terms, how central is a node, a person in a network will have an impact on how fast an infectious disease could spread.
Centrality might not be a property of a node, an individual alone. In some cities the disease can spread faster than in others. Some cities like New Delhi taken as a whole might have a high centrality. We have a Monday evening market where I live and people gather in large numbers to buy vegetables and other things and they do meet their neighbours and friends over there.Some cities might have low centrality where people usually do not come together in large numbers and interact with each other.
Sometimes, it is not how central a person is in the network that affects the spread of a disease but the gate keepers or bridges who connect multiple networks.
While it is difficult to map these networks in our community and take preventive action, a general awareness about how infectious diseases spread through social connections and how some people could accelerate this spread is useful. If you happened to be a Hub with so many connections and social interactions or a connector or a bridge, you need to be more careful and aware so that your proactive actions could reduce the spread.
Disclaimer: The views expressed in the article above are those of the authors' and do not necessarily represent or reflect the views of this publishing house. Unless otherwise noted, the author is writing in his/her personal capacity. They are not intended and should not be thought to represent official ideas, attitudes, or policies of any agency or institution.