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Behind the Curve: Understanding and Preparing for Exponential Growth

Following the growth of the pandemic is absolutely essential for those charged with the task of planning for the future of their communities. This role can include but is not exclusive to government officials, hospital administrative workers, health care providers, school administrators and individuals who want to track the daily growth of the pandemic. Difficulties in understanding timing particularly arise due to the logarithmic models behind epidemiology, especially exponential growth. In a study conducted by MIT, they found that people have difficulty understanding how quickly something will grow (or decay) following this model. It is important to emphasize that this is an issue beyond mathematical reasoning, rather one that is inherent to us: the logarithmic model is not naturally intuitive.

While the term “flattening the curve” has been universally adopted and generally understood, it does not give background on just how quickly a “wave” could rise. Many people experience what is called exponential growth bias, a documented phenomenon in psychology in which an individual interprets exponential growth as a linear model. This miscalculation can lead to underestimation and potential planning mistakes. In a study done by Levy and Tasoff on the effects of exponential growth bias on decision making, they found that difficulty in mentally calculating the rate of exponential growth lead to overconfidence when taking out loans. This concept can be similarly applied to the coronavirus pandemic. For those with the important role of planning for their communities, overestimating the amount of time it would take for an outbreak to expand could have very serious consequences. Timing is key in stockpiling supplies and putting restrictions in place.

Some methods that can be used to mitigate this effect and to make conservative estimates as relating to pandemic growth are as follows:

  1. As suggested by the Levy paper, following model simulations could be worthwhile for those who need to make high risk decisions. The growth of the virus can be swift and unexpected and following exact estimates could help plan appropriately and likely give more conservative estimates. These are not always 100% accurate. In the United States it was expected that Florida would experience a large outbreak sometime in April, and its spike came in July. These early estimates allowed the state to build up its supplies which could have impacted the state’s low fatality rate.

  2. It can also be helpful to communicate the rate of growth with standard reference points. An example would be to say that in the first 5 days, there is an expected increase of 15 daily cases. In the next 3 days there could be an increase of 40 daily cases, and so on. As the rate of an outbreak is not linear this measurement would be changing every few days or so on, but estimates like this would help communicate the present and expected situation of the outbreak.

  3. Another helpful method to understanding the speed of the exponential spread is to pay attention to visceral markers. Early signs of this could include a general population’s lack of concern concerning the pandemic, a vibrant city social scene or a large outbreak in an area that is easily travelled to and from. An example of this would be an individual in Rome hearing about a large outbreak in Milan. Secondary markers to this could include longer lines at testing centers, an increase in mask usage on the street or an increase to usual travel in and out of the area. Definite signs that an outbreak is reaching a peak or increasing rapidly are the filling of emergency rooms to capacity, the selling out of essential supplies (like ventilators or masks) or the shuttering of businesses.

  4. First person accounts from those who have already experienced the peak of the outbreak can also be extremely beneficial. From learning from other’s personal experiences one can prepare for the less obvious problems that could arise. These could include the incredible emotional and mental burden of medical staff working with coronavirus patients, a general population’s increase in mental health difficulties, or an exodus of many wealthier individuals from the city. Preparing for an outbreak can go beyond increasing hospital capacity or delaying schools, there is also an incredible emotional burden that is important to prepare for.

  5. Beyond just this, while the pandemic has brought exponential growth to center stage, there are many examples of exponential growth in daily life. These include credit card debt, a house fire, or the decay of food. To help paint a picture of how quickly outbreaks can expand using these comparisons could help give communities a greater sense of urgency.


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