COVID-19 pandemic measures were a milestone in how modern Western societies restricted freedoms in the face of a new pathogen. It’s fair to say that we panicked in those fateful spring months of 2020. Ever since, the heated conversations, angered populations, lost friendships, and moralistic battles have split societies down the middle.
Did lockdowns “save lives” and “stop the spread” as promised?
To gauge a large and sprawling field, scientists use meta-studies—a kind of methodological studies that systematically search for studies and incorporate their result into a combined whole.
Jonas Herby of the Center for Political Studies in Copenhagen, Denmark, Lars Jonung of Lund University, and Steve Hanke of Johns Hopkins have done just that. In ‘A Literature Review and Meta-Analysis of the Effects of Lockdowns on Covid-19 Mortality’, just published as a working paper with Johns Hopkins’ Studies in Applied Economics series, they assemble the evidence that lockdowns averted deaths from COVID-19.
Since there’s a lot of scope for fiddling with studies that make up a meta-analysis, here’s the full selection strategy that the authors used :
👉 They screened over 18,000 studies, most of which weren’t related to the narrow lockdown efficacy question.
👉 1,048 studies remained, where most were excluded for not answering the two core eligibility questions:
- Does the study measure the effect of lockdowns on mortality?
- Does the study use an empirical diff-in-diff approach?
👉 Of the 117 studies that remain, the authors exclude 83 that were duplicates, used modeling, or synthetic controls. Structural-break studies weren’t enough, the authors argue, “as the effect of lockdowns in these studies might contain time-dependent shifts, such as seasonality.”
34 studies made it into their analysis, and they are divided into three segments: mortality impacts associated with the stringency of COVID-19 policies; Shelter-in-Place studies; and studies that target specific non-pharmaceutical interventions.
The authors are pretty severe in their final conclusions. Lockdowns didn’t meaningfully reduce COVID-19 mortalities: “the effect is little to none.”