Physical Distancing: 3 Feet vs 6 Feet

A Brief Overview

This study compared rates of COVID in school districts that implemented 3-foot physical distancing policies and those that implemented 6-foot physical distancing policies, and controlling for community spread found that there were not significant differences between them. This is important research — it reflects empirical testing of policy implementation, something we should be doing more often!

Limitations of the Study

Despite providing very clear analysis, there are also important limitations we should consider when deciding how this study informs our behavior. There are four main critiques of the study that I’ve seen floating around, and I would like to take a moment to discuss each one.

1. Policy vs Behavior

A key limitation of this study is that it focuses on written policies rather than observed behavior. As anyone who has left their house in the past 12 months knows, these are very different things. As we’ve seen, schools with 6-foot distancing policies and universal masking requirements are often not consistently or meaningfully enforcing them (1 2 3) . As documented in recent research from the CDC (Gold et al., 2021), even in schools where 6 foot policies were in place it was not always possible to seat students more than 3 feet apart due to classroom layouts and the need for small group activities. The found that while mask compliance was high during observations, they were removed entirely during in-classroom lunches that “might have facilitated spread”. There were also specific instances of “lack of or inadequate mask use” were identifiable in five clustered outbreaks.

2. Reported vs Actual Cases

An issue that’s recurrent in COVID research is that it’s often difficult to get accurate measurements of cases in the community. Because some people (particularly children and teens) may only have mild symptoms or be asymptomatic, they may never seek out testing; in other cases people with clear and pronounced symptoms may avoid testing for financial, political, or social stigma related reasons and thus not be represented in the data. Asymptomatic and symptom disregarded cases are of particular interest when considering children, as they are more likely to have milder symptoms and families may feel economic pressure to avoid having kids stay home sick. In this study, only cases which were reported to schools and subsequently to the state were included, and surveillance testing was not widely used. The authors do acknowledge this limitation:

3. Community Spread vs School Spread

The goal of school-based mitigation policies is to reduce or prevent the spread of COVID in the school environment, where the group education setting provides a higher risk environment for transmission of respiratory diseases. Ideally, studies would be able to focus solely on the infections that occur in this space, but in reality it is very difficult to separate community-based spread from school-based spread. This is because many infections are not reported, and because school staff and student’s membership in the community creates a potential bidirectional relationship between community and school infection rates. As a result, studies often rely on tracking clusters of cases with known contacts.

4. Safe vs Safer

An area of disconnect between media reporting and the study itself is on the issue of “safety”. Safety is inherently difficulty to assess, as it ultimately requires a subjective evaluation of the degree of risk that’s acceptable relative to the potential benefits. Perfect safety — zero risk — isn’t possible short of closing schools indefinitely.

Summary & Conclusion

Ultimately, the study is an important piece of information — it shows us that the policies don’t differ significantly. What it doesn’t tell us is why. It could be that we’ve been enforcing more distance than required. It could be that we’ve been failing to enforce distancing, making the policy difference moot. It might even be that 6-feet was always inadequate for a classroom setting, and 9 feet would be necessary to reduce transmission. It could be that other failures of mitigation, like maskless classroom dining and poor ventilation, provide enough risk that any benefits from distancing were erased. And regardless of the cause, we don’t know if any of this is generalizable to adults, or outside of a school setting yet.

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