Weekend Reads | Learning from Lockdowns

by Kevin Schofield

This weekend's read is an article from the journal Nature looking at what scientists have learned from studying the results of various government measures to stem the spread of COVID-19 — and especially from lockdowns.

First, and perhaps the main finding, is that drawing conclusions on the impact of lockdowns is tricky business. What makes it hard turns out to be many of the classic challenges with conducting scientific research.

The question we really want to ask is, "How much of an impact did lockdowns have compared to what would have happened without lockdowns?" That's called a counterfactual: an outcome that did not occur, but could have under different circumstances. Counterfactuals can't be tested directly, or at least not until someone invents a time machine so we can go back and change what really happened. So researchers instead try to find the best point of comparison to another place that is very similar, except for the one thing that's being tested. So, for example, if we wanted to know what would have happened to Seattle without a COVID-19 lockdown, we might look to other U.S. cities with similar population demographics and economic bases that chose not to lock down (admittedly a very small set).

Trying to identify such points of comparison highlights the second problem: Most places adopted multiple measures to fight COVID-19, so the effects of those measures are all conflated. That makes it nearly impossible to tease out the impact of just the lockdowns.

The third problem is the "comparing apples to oranges" issue: Lockdowns took several different forms. Some cities and states issued broad "stay at home" orders, while others closed schools and businesses, and still others banned large gatherings, small gatherings, indoor gatherings, and travel across borders. And, of course, many adopted a mix of these kinds of lockdowns.

To the extent that researchers have been able to draw conclusions, they found a big difference between the initial wave of COVID-19 in early 2020 and the second wave later that year. In the first wave, when we knew little about the virus and how it spread, countries that adopted a "go hard, go fast" policy of lockdowns tended to fare better. It particularly helped isolated countries such as New Zealand that could close their borders largely before the virus arrived at their shores. But the effectiveness of lockdowns depended heavily on citizens' willingness to comply, and on the government's ability to enforce them; in countries such as Peru, a lockdown policy simply wasn't effective, because the structure of society made it impractical and it couldn't be enforced.

During the second wave of COVID-19, however, things changed — and the point of comparison changed. By then, we knew much more about COVID-19, how it spread, and how often it resulted in serious illness or death. Asking "How much of an impact did lockdowns have?" meant comparing it with places where people would still take many of the precautionary measures that help slow the spread of COVID-19 — wearing masks, social distancing, washing hands, avoiding indoor gatherings — even without a government-imposed lockdown. Researchers have concluded that second-wave lockdowns thus had a much smaller impact.

And then there's the flip side: Lockdowns reduced the spread of COVID-19, but they also had their own negative effects. They dramatically decreased economic activity, shuttering restaurants and businesses and putting many people out of work. They also increased social isolation and mental health issues for many, interrupted standard health care, and disrupted students' education. Again, though, we need to ask the counterfactual: What would have been the effect on the economy, personal mental health, health care, and education without lockdowns? That's tough to say, though at least on the economic front, there is evidence that the places that locked down quickly also had the quickest economic recovery.

The article discusses the lessons learned for the remainder of this pandemic (China's "zero COVID" policy of continued lockdowns may be more harmful than helpful at this point), but raises some good points about lessons we might apply to the next pandemic. "Go hard, go fast" seems like a good initial strategy, though all of our practice and experience with COVID-19 might mean that we will adopt precautionary measures much faster and reduce the comparative impact of first-wave lockdowns. But whatever measures our government takes, we can hope it has also learned important lessons in how to address the disparate impacts of lockdown policies on underprivileged communities, as well as in how to be more transparent about how the policies are decided.

What scientists have learnt from COVID lockdowns

Featured image by Corona Borealis Studio/Shutterstock.com.