University of Washington model shows effects of visiting one friend during social distancing

Pedestrians walk past coronavirus-themed artwork of a person wearing a mask and gloves that was painted by street artists @theydrift and @ksra_ksra on a boarded-up business in Seattle's Capitol Hill neighborhood, Tuesday, April 7, 2020. Street art has sprung up on boards covering the windows of many businesses in the area closed temporarily due to the outbreak of the coronavirus. less Pedestrians walk past coronavirus-themed artwork of a person wearing a mask and gloves that was painted by street artists @theydrift and @ksra_ksra on a boarded-up business in Seattle's Capitol Hill ... more Photo: Ted S. Warren, AP Photo: Ted S. Warren, AP Image 1 of / 1 Caption Close University of Washington model shows effects of visiting one friend during social distancing 1 / 1 Back to Gallery

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As the weeks of social distancing guidelines and stay-at-home orders drag on, many Seattleites may begin feeling isolated and start wondering: is it really that harmful to visit a friend during quarantine?

Which is why researchers at the University of Washington created a new model called "Can't I please just visit one friend?" to illustrate just how visiting someone outside your immediate household contributes to the overall community transmission of the disease.

The analysis starts by taking a sample of 200 houses before the spread of the virus. Of those 200 houses, each household has an average of 15 social interactions with other households in the community, creating a network in which every house can be reached by at least one path. In this pre-social distancing scenario, the average household has 199 other houses within 3 degrees of separation, a model of connection used throughout the model.

"Three degrees of separation represents someone you might have some sense of—someone in a household connected to a household connected to a household connected to you," the researchers wrote. "Someone at that distance has a pretty good chance of transmitting COVID to you (if they’re infected) or you to them (if you’re infected)."

Next the researchers model what perfect isolation would look like using the same sample of 200 houses. In this ideal isolation model, the virus could spread between members of the same household, but would quickly die as no one outside of the house is interacting with each other.

However, this model is not possible, as essential functions of society require people like doctors, first responders, transit operators and grocery store clerks to continue working. So the next model builds upon perfect isolation and postulates that 1 in every 10 households contains someone with a job where they need to continue working, exposing them to other people.

The addition of essential workers means the more households become exposed to the virus. The largest cluster created by these connections encompasses 26.5% of households, with the average household having 4.2 other households within 3 degrees of separation.

"The virus has some opportunity to move around here. This means that some people are going to get infected, and some people are going to die," wrote the researchers. "But these connections are so essential to the health and well-being of all of us that we as a society are willing to make that trade-off."

With Washington's current stay-at-home orders that has closed all nonessential businesses, this model most closely represents Seattle's situation which is currently seeing reduced transmission rates as a result of physical distancing -- unless people start visiting their friends or family who are not part of their immediate households.

If two people in each household decide to maintain an in-person social connection with one person from another household, 71% of houses in the community are now connected to each other. While the interaction with one friend may be seemingly harmless, it causes the average household to have 12.1 other households within 3 degrees of separation from them and 52.6 within 6 degrees, allowing for quicker transmission.

What lessons can be learned from this model? While recognizing that humans are inherently social and limiting networks can be a challenge, the researchers are succinct with their judgement that continued social distancing is needed in this time: "Every additional connection that we can postpone until COVID-19 is under control has the potential to save one or more lives. Yes, every one."

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