Americans have mixed views of social distancing. Yet, there is evidence that social distancing is an effective non-pharmaceutical measure taken to prevent the spread of a contagious disease, such as COVID-19. Social distancing means keeping your distance from other people, and to reduce the number of times you might come in contact with other people. Thus, the need for people to heed “stay in place” requests, or orders.

Infectious diseases spread in a typical pattern that is shown in the Tweet from the CDC Twitter account. Right now, the U.S. is in the “acceleration” phase of the COVID-19 pandemic. Depending on where you live, the nature of this curve will depend upon conditions on the ground. For example, if there is no intervention, then it is possible for the height of the curve to be much higher than locations that implement social distancing. Some people think letting the disease run its “coarse” is an option they prefer. The President of the United State, up to a day or so ago, wanted to send people back to normal life on Easter Sunday. What experts on the task force said about this plan, convinced him not to go ahead with this policy, or face a disaster.

COVID-19 Trend Today

A question to ask based on the CDC model for the growth of a pandemic is this: Where are we right now with COVID-19 as a global community? Are we in the acceleration phase (upward trend), the peak, or in deceleration? To answer this question, I found data on the Humanistic GIS Lab at University of Washington – Seattle. The figure below shows four plots, and all of them are trending upward, with the aggregate confirmed and active confirmed in the acceleration phase of the disease. Although this is data for the world, it gives us a real time measure of the disease at this time.

How Can We Decelerate the Coronavirus?

Since there are no medicines or vaccines for the coronavirus, non-pharmaceutical public health intervention measures are considered the best way to mitigate the risk and impact of the infectious disease.

Although not all U.S. states have adopted the same measures, most have implemented some form of social distancing. As shown in the graph below, an intervention of social distancing would “flatten the curve” of the pandemic outbreak. If the curve is not flattened, health care is threatened, and hospitals face a severe disruption. We are witnessing horrific scenes in New York hospitals because of the influx of COVID-19 patients.

Where’s the Evidence that Social Distancing Works?

Does social distancing have an effect on the spread of an infectious disease. There is much research to support the use of social distancing.

One source of evidence is research that has been done to find out what happened when U.S. cities used social distancing to mitigate the effects of the 1918 Flu pandemic. By the end of the pandemic, between 50 and 100 million people were dead worldwide, including more than 500,000 Americans.

An important study by Markel, Lipman, Navarro, et.al. looked at the effect of social distancing used during the 1918-1919 Influenza Pandemic. (Markel H, Lipman HB, Navarro JA, et al. Nonpharmaceutical Interventions Implemented by US Cities During the 1918-1919 Influenza Pandemic. JAMA. 2007;298(6):644–654. doi:10.1001/jama.298.6.644).

There were no computers or online data bases in 1918. But, there were paper documents kept by municipalities during this period. The researchers used public health documents and the type of non-pharmaceutical interventions implemented around the country including school closure; cancellation of public gatherings; and isolation and quarantine.

They looked at weekly excess death rate (EDR); time from the activation of nonpharmaceutical interventions to the first peak EDR; the first peak weekly EDR; and cumulative EDR during the entire 24-week study period.

You’ve heard Dr. Deborah Birx and Dr. Anthony Fauci tell Americans that we need to “flatten” the curve. What the study of the 1918 pandemic found was that the curve can be flattened if communities practice social distancing.
However, the results will depend on many factors.

Let’s take a look at Social Distancing

Notice that in 1918, it took several months to flatten the curve. In order to mitagate against the virus, social distancing can work, but it has to be implemented over a longer time period than the White House Coronavirus Task Force would like to admit.

Finally, I want to show you additional graphs of four cities, and the types of interventions they implemented. Their results are important to understand. First, take a look at the four graphs. All cities eventually flattened the curve. But note that each graph is unique. Two have one peach, while the other two have two peaks. Let’s find out why.

Please notice that below the graphs are black lines that show the types of interventions used to mitigate against the virus:

• School Closure
• Public Gathering Ban
• Isolation, quarantine

The most effective appears to be isolation and quarantine, as used in New York City. From the date of the first case detected in New York, September 8, it took until December 1 for the curve to flatten. Take a look at Denver. It took much longer For the city to flatten the curve. Notice that they implemented school closure and banned public gatherings. However in mid-November, they relaxed these methods, and the number of cases increased resulting in a second peak. After they took kids out of school for a second time, and implemented isolation, and quarantine, the curve was flattened.

Conclusions

The lessons from the 1918 Flu epidemic are clear. Non-pharmaceutical methods, including keeping students out of school, banning public gatherings, and isolation, and quarantine are effective. They can mitigate the spread of a virus.

Shelter in place was just announced by the Governor of Georgia. The data from the 1918 Flu epidemic supports this decision.