Social Distancing May Worsen Epidemic Outcomes

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Social distancing requirements could have counterintuitive outcomes, according to one study, which suggests the behavioral changes triggered by social distancing could ultimately worsen the disease outcome and increase the size of the final epidemic

During an epidemic or pandemic, public health officials may enforce social distancing as a method to control the spread of a pathogen. However, at least one study suggests the ultimate changes in contact patterns triggered by social distancing measures could end up having a negative effect on the population and, in some cases, even worsen the outcome of the epidemic.[i]

The practice of social distancing means keeping physical space between yourself and other people outside of your home. The U.S. Centers for Disease Control and Prevention (CDC) states that in order to practice social distancing, you must stay at least six feet (two meters) away from other people, not gather in large groups and avoid crowded places and mass gatherings.[ii]

Click to read the full study.

According to the CDC, "Limiting face-to-face contact with others is the best way to reduce the spread of coronavirus disease 2019 (COVID-19),"[iii] and various levels of social distancing requirements have been enforced around the globe during the COVID-19 pandemic. However, as noted by researchers in the Journal of The Royal Society Interface, "In general, it is hard to predict the effect of preventive measures without using models to guide us."[iv]

This is particularly true when it comes to accounting for human behavior, which is often assumed to be constant over time by standard epidemic models but, in fact, may be quite dynamic, especially during a public health crisis.

Study Demonstrates Potential Negative Outcomes of Social Distancing

To determine whether social distancing could have unexpected negative outcomes, researchers from Stockholm University in Sweden and the U.K.'s University of Nottingham used epidemic network models and existing real-world networks. The results suggest that social distancing, when conducted at a "high enough rate" at the start of an epidemic, may prevent it from occurring.

However, moderate social distancing may worsen the disease outcome both in the initial phase of the outbreak and in terms of the final epidemic size. As an epidemic evolves, people may choose to distance themselves from those they know are infectious. Models suggest that social distancing may even arise spontaneously during an epidemic based on individual choices rather than being centrally imposed.[v]

An individual may then choose to either drop the connection completely or replace ("rewire") the connection with another individual, perhaps because they desire to maintain a certain number of social connections. This is where many of the negative implications arise, as the study found that:

" … having individuals who rewire away from infectious neighbors and possibly replace them with new ties may be harmful for the community as a whole.

Depending on the network structure of the population, social distancing may in fact increase the epidemic threshold parameter from below to above its threshold value, making a large outbreak possible where without social distancing it was not. We also show that social distancing can increase the final size of the epidemic."[vi]

While this didn't hold true for all networks, there were both real-world networks and model networks that the researchers found had worse outcomes when social distancing was in place. This means, according to the researchers, that social distancing may have "counterintuitive consequences for the population-level."[vii]

Further, they noted, "Public health interventions that aim at changing individual behavior through social distancing could have adverse consequences," using the example of school closures, stating that while such closures reduce social contacts between the children and their schoolmates, some of these contacts may be replaced by contacts outside of the school.

"As our results show, it is not necessarily straightforward what effects such behavior may have at the population level, where much may depend on the disease and population under consideration," they noted.[viii]

This echoes a 2012 study published in BMC Public Health, which similarly found that social distancing can backfire, particularly if not done at a "drastic" level at the very start of an epidemic, at which point foregoing control and allowing the epidemic to run its course is preferable.[ix]

In some cases, social distancing can contribute to the "worst outcome," according to the BMC Public Health study, when control is attempted but not at the level that suppresses the epidemic:

"If a disease is very highly infectious, social distancing may have no effect, or may require an unfeasibly high degree of caution in order to be effective. In these cases, doing nothing will be a more cost-effective strategy than using social distancing, because the worst-case outcome arises if the control is applied, but the level of caution used is too weak."[x]

Consequences of Social Distancing Cannot Be Ignored

Aside from its effects on the spread of pathogens, there are adverse consequences of social distancing, like resulting social isolation, that are worthy of attention. At least 13 studies demonstrate that social isolation increases mortality risk, while having fewer social ties may increase your susceptibility to viruses like the common cold.[xi]

Social isolation also increases inflammation in your body,[xii] making you more vulnerable to inflammation-linked chronic diseases like cancer and, ironically, possibly increasing your predisposition to lung infections like pneumonia.[xiii]

It's clear that infectious disease dynamics are complex and only beginning to be understood, and seemingly straightforward "solutions" like social distancing do not have straightforward effects. In some cases, it may even worsen, not improve, epidemic outcomes.


References

[i] J R Soc Interface. 2018 Aug; 15(145): 20180296.

[ii] U.S. CDC, Social Distancing, Quarantine, and Isolation

[iii] U.S. CDC, Social Distancing, Quarantine, and Isolation

[iv] J R Soc Interface. 2018 Aug; 15(145): 20180296.

[v] BMC Public Health. 2015 Sep 28;15:973. doi: 10.1186/s12889-015-2336-7.

[vi] J R Soc Interface. 2018 Aug; 15(145): 20180296.

[vii] J R Soc Interface. 2018 Aug; 15(145): 20180296.

[viii] J R Soc Interface. 2018 Aug; 15(145): 20180296.

[ix] BMC Public Health 12, 679 (2012).

[x] BMC Public Health 12, 679 (2012).

[xi] JAMA. 1997 Jun 25;277(24):1940-4.

[xii] Neuroscience & Biobehavioral Reviews May 2020, Volume 112, Pages 519-541

[xiii] Clin Chest Med. 2018 Dec; 39(4): 669-676.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of GreenMedInfo or its staff.
Sayer Ji
Founder of GreenMedInfo.com

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