I wrote this in another context and thought that some folks here might find it useful. It doesn’t include anything specific to J-pouches or IBD, but the current pandemic seems to be on most people’s minds.

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I’m reading and hearing a fair amount of miscalculation and oversimplification of risk during the current COVID-19 epidemic. I thought it might be helpful to discuss this a bit more carefully, mainly so people can make considered choices about the risks they must take and the risks they choose to take. My most important point is this: sending the least vulnerable member(s) of your household into a potentially infectious situation does not protect other household members from that risk. For this purpose I’ll distinguish three categories of risks: personal risks, household risks, and community risks.

Personal risk is the easiest to understand, although it tends to get exaggerated. One constructive reason for exaggerating personal risk is to use it to better account for the other, more easily neglected risks. If I’m overly afraid of my own risk I’m less likely to put my household and community at increased risk. Personal risk is simply the risk of personally contracting COVID-19 and it broadly entails several potential bad outcomes: minor illness, major illness (requiring hospitalization), and death. Asymptomatic illness isn’t a bad personal outcome, though it can be devastating to a household. The likelihood of death from infection rises substantially when hospital resources are too stretched to provide adequate care, essentially converting a major illness into a lethal one.

Personal risk is entirely incurred through direct or indirect contact with an infectious person. Notions of direct contact are evolving, as evidenced by the recent CDC suggestion to wear a cloth face covering in public settings where other social distancing measures are difficult to maintain. There’s nothing magical about a six foot radius. The actual “safe distance” will vary enormously depending on air flow, and walking through a cloud of microdroplets recently produced by an infectious person will likely be high-risk even if they have moved on and are nowhere near you. Surfaces that have been touched (or exhaled onto) by many people are much riskier sources of indirect contact than surfaces that have been exposed to one or two. Other than exaggerating the safety of a six-foot radius, most people seem to have a reasonable grasp of personal risk.

Household risk is often misunderstood. The basic idea is that the risks (of infection) to the members of your household are roughly equal to the sum of all of the risks taken by every member of the household. Whenever your household’s “bubble” is breached, whatever comes through that breach will tend to touch everyone. Because transmission occurs before symptoms, and household members tend to be substantially and repeatedly exposed to one another, a single infected person producing vast numbers of virus particles is very likely to transmit the disease within a household. Bringing contaminated objects into a household also introduces risk, but much less than bringing an infected person into a household. So, for example, sending a younger family member to the grocery store may seem safer (i.e., a lower risk of fatal illness), but it probably introduces about as much risk to the household as any other equally careful shopper.

Community risk is the most misunderstood of all. At the early stages of an epidemic, when only a small number of people are infectious, each individual encounter is very low risk. Even group gatherings are (individually) low risk activities. When thousands of these encounters occur, though, some of them are sure to spread the virus. If we apply only personal risk standards we have too many such “safe” encounters and get a terrible community result, which eventually makes future personal risk very high anyway. Thus it seemed reasonable to Spring breakers to gather on beaches: most of them caught nothing, and a small fraction of them jump-started a huge problem.

In the long run these three risks combine. You and those you care about are ultimately only as safe as the household and community you interact with. It’s best to undertake any necessary risks with an honest assessment of their magnitude and downstream effects, and to mitigate them to the degree possible.