Coronavirus: Does social distancing work?

When researchers want to determine if a new therapy has a beneficial clinical effect, they conduct a randomized trial. They divide the population to be studied into different groups, some of whom will receive the treatment being evaluated and others who will not. The outcomes in the different groups are then studies to see if the therapy had any significant effects, both beneficial and detrimental. The purpose of randomization is to try and make the different groups similar to each other, so that, for example the average age or proportion of women is more or less equal. The idea is to apply different treatments (the one of interest, and either placebo or some other intervention) to more or less similar populations to allow observation of the effects of the intervention.

Conceivably, one might also observe differences if the same intervention were to be applied to groups having different characteristics. In this case, however, it is much more difficult to determine if the intervention does anything, because differences between the groups might account completely for differences in outcome. There is however, one observation that can be made: whether the intervention works for all groups regardless of differences between them. This is the situation we have with the social distancing and stay at home orders currently affecting the majority of the United States. While we cannot say for certain that social distancing does or does not work, we can say that it does not work the same everywhere. The experiences of New York and California discredit the idea that the spread and effects of the Wuhan coronavirus are simply matters of a nasty virus and avoiding non-essential travel.

It is not possible for anyone to say that earlier social restrictions or government intervention would have contained the spread of the spread of the virus, or that the death count would have been higher had not such efforts been imposed, nor is it possible to say they had no benefit. There is simply no way to know. It seems reasonable that the less interaction people have with each other, the less likely an infected person is to spread the infection during the interval in which that person is contagious. Thus, social distancing is reasonable. But, as is possibly the case with hydroxychloroquine, social distancing and isolation are only discrete factors among many that contribute to the profile of disease spread. They may influence some aspect, such as rate of spread, and thus impede, but not control the virus. The experience in New York suggests that either social distancing has only second order effects, or that the environment of New York makes social distancing efforts either less effective or less practical.

What the disparate results of social distancing policies suggests is that the spread of the virus depends on conditions, that is , the environment in which it spreads, of which social distancing is only one factor. The spread of the virus is likely governed by processes of which we, including our most esteemed experts, are unaware. The virus interacts with the environment as a constituent of a system, likely involving complex interactions, and un-accounted-for processes. It is obvious that viruses have no cognition, that they devise no strategies nor coordinate no actions. The same is true of water molecules, yet snowflakes form with symmetry and remarkable consistency in many of their characteristics, responding only to the conditions in which they form, and the inherent characteristics of water. Epidemics may behave the same way. Just as conditions determine the ultimate shape of snowflakes, they determine how fast and how far coronavirus spreads, and how many people are asymptomatic and how many people die.

What our experience tells us to date is that social distancing and isolation are reasonable, but also that we have no real idea of how effective they are.