Does Social Distancing Work?: Some Historical Perspective

Social Distancing

Over at the Microbial Menagerie, microbiologist Jennifer Tsang argues that social distancing helped to slow down the 1918 Influenza Pandemic (Spanish flu) and it just might work for the Coronavirus as well.

Here is a taste of her piece:

…do social distancing measures actually work?

To answer this question, let’s take a look at the response of several cities during the 1918 influenza pandemic. A 2007 paper in PNAS documented the effects of the 1918 pandemic in various US cities based on when public health interventions began, what the interventions were, and how many interventions they enforced. Examples of public health interventions include isolation policies, closures of schools, churches, and other venues, bans of public gatherings, and more.

Cities that began interventions earlier had significantly lower peaks of pneumonia and influenza-related mortality. And cities that implemented four or more interventions had a lower median peak weekly death rate (65/100,000 people) versus 146/100,000 people from cities with three or fewer interventions.

The response between Philadelphia and St. Louis made a great case that social distancing does work. In Philadelphia, the first case was reported on Sept 17 and authorities downplayed the significance of the case. They even allowed a city-wide parade to happen on Sept. 28. School closures and bans on public gatherings did not happen until Oct.3, 16 days since the first case. Meanwhile, St. Louis had its first case on Oct 5 and the city implemented social distancing measures two days later.

What was the effect? The 14-day difference in response time between the two cities represents approximately 3-5 doubling times for the epidemic. The peak weekly death rate from pneumonia and influenza-related deaths was 257/100,000 people in Philadelphia. The same metric in St. Louis was 31/100,000.

Read the entire piece here.  HT: John Haas on Facebook.