A Literature Review and Meta Analysis of the Effects of Lockdowns on COVID 19 Mortality

Today, it remains an open question as to whe<strong>the</strong>r lockdowns have had a large, significant effect
on COVID-19 mortality. We address this question by evaluating <strong>the</strong> current academic literature
on <strong>the</strong> relationship between lockdowns <strong>and</strong> COVID-19 mortality rates. 3 We use “NPI” to
describe any government m<strong>and</strong>ate which directly restrict peoples’ possibilities. Our definition
does not include governmental recommendations, governmental information campaigns, access
to mass testing, voluntary social distancing, etc., but do include m<strong>and</strong>ated interventions such as
closing schools or businesses, m<strong>and</strong>ated face masks etc. We define lockdown as any policy
consisting <strong>of</strong> at least one NPI as described above. 4
Compared to o<strong>the</strong>r reviews such as Herby (2021) <strong>and</strong> Allen (2021), <strong>the</strong> main difference in this
meta-analysis is that we carry out a systematic <strong>and</strong> comprehensive search strategy to identify all
papers potentially relevant to answer <strong>the</strong> question we pose. We identify 34 eligible empirical
studies that estimate <strong>the</strong> effect <strong>of</strong> m<strong>and</strong>atory lockdowns on COVID-19 mortality using a
counterfactual difference-in-difference approach. We present our results in such a way that <strong>the</strong>y
can be systematically assessed, replicated, <strong>and</strong> used to derive overall meta-conclusions. 5
2 Identification process: Search strategy <strong>and</strong> eligibility criteria
Figure 3 shows an overview <strong>of</strong> our identification process using a flow diagram designed
according to PRISMA guidelines (Moher et al. (2009). Of 18,590 studies identified during our
database searches, 1,048 remained after a title-based screening. Then, 931 studies were excluded,
because <strong>the</strong>y ei<strong>the</strong>r did not measure <strong>the</strong> effect <strong>of</strong> lockdowns on mortality or did not use an
empirical approach. This left 117 studies that were read <strong>and</strong> inspected. After a more thorough
assessment, 83 <strong>of</strong> <strong>the</strong> 117 were excluded, leaving 34 studies eligible for our meta-analysis. A
table with all 83 studies excluded in <strong>the</strong> final step can be found in Appendix B, Table 8.
3
We use “mortality” <strong>and</strong> “mortality rates” interchangeably to mean COVID-19 deaths per population.
4
For example, we will say that Country A introduced <strong>the</strong> non-pharmaceutical interventions school closures <strong>and</strong>
shelter-in-place-orders as part <strong>of</strong> <strong>the</strong> country’s lockdown.
5
An interesting question is, “What damage lockdowns do to <strong>the</strong> economy, personal freedom <strong>and</strong> rights, <strong>and</strong> public
health in general?” Although this question is important, it requires a full cost-benefit study, which is beyond <strong>the</strong>
scope <strong>of</strong> this study.
5