#Flattenthecurve: Understanding the Collective Benefit of Social Distancing

The concept that strict social distancing will decrease our individual risk of contracting COVID-19 serves as a powerful incentive to adhere to guidelines and recommendations (fortunately).  The actual reduction in risk of eventually contracting the virus through social distancing is likely much more modest than we hope.  This virus is highly contagious, and we are all still at high risk of eventually getting it.  Paradoxically, social distancing will make the pandemic last longer than the usual social free for all. 

The real goal of social distancing is to stagger the infections over a longer time period with the goal of decreasing the case fatality rate (CFR) rather than the total number of cases.  In other words, by practicing social distancing, the goal is to decrease the risk of death from infection rather than the total number of cases (although it may do both to some extent).

I discussed case fatality rate in my previous blog.  Essentially, it is the rate of death among patients confirmed to have the infection.  Many factors impact case fatality rate (virulence of the pathogen, ascertainment bias/testing enough people to include mild cases, effective drugs to reduce the severity of the illness, access to resources needed to manage the most severe cases, etc).  Since we cannot reduce the virulence of the virus and we currently have no effective drugs to decrease the severity, the only variable we can control is access to resources.  In the case of COVID-19, that means ICU beds, ventilators, and ECMO (cardiopulmonary bypass). 

Northern Italy’s failure to enact strict social distancing measures caused a surge in infections early in their epidemic.  The results have been catastrophic.  Doctors are in the terrible position of rationing ICU beds and ventilators to the youngest, healthiest patients that have the most life years ahead of them and will most likely recover more quickly to make the ICU bed/vent available to someone else.  This surge has led to a CFR of 7%, twice the CFR in the Hubei Province of China where draconian isolation measures were enforced by the state.  In contrast, S. Korea has a CFR <1%.  While you have to be careful comparing CFR in different populations because of difference in ascertainment bias (the wide availability of tests in S. Korea likely reduced its CFR by including milder cases in the analysis), the large gap in CFR between N. Italy and S. Korea is still likely related to the difference in effective social distancing implemented early in the pandemic.  Spreading out the infections over a longer period of time prevents the ICU beds/vents/ecmo from becoming saturated.  So if you or your loved one needs a ventilator to support oxygenation/gas exchange while your body fights the infection, it will be available.  Sadly, despite appropriate social distancing measures now in place in N. Italy, the CFR remains high.  The horse is out of the barn.  Social distancing works best when applied early and strictly.  Everyday, our government reissues more strict isolation measures.  Start aggressive social distancing now and stay ahead of the curve and the reactive rather than proactive guidelines issued by our government.

#flattenthecurve #stopthesurge

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