The supporting documentation is long and complex and I don't expect anyone to read it all. But I include the link anyway.
Some professors from the Johns Hopkins Institute for Applied Economics, Global Health, and the Study of Business Enterprise did a meta-analysis of the effectiveness of "compulsory, non-pharmaceutical interventions" (e.g. lockdowns) on COVID-19 mortality.
The short version:
Lockdowns have had little to no effect on COVID-19 mortality.
The longer, but more detailed, policy implications:
In the early stages of a pandemic, before the arrival of vaccines and new treatments, a society can respond in two ways: mandated behavioral changes or voluntary behavioral changes. Our study fails to demonstrate significant positive effects of mandated behavioral changes (lockdowns). This should draw our focus to the role of voluntary behavioral changes. Here, more research is needed to determine how voluntary behavioral changes can be supported. But it should be clear that one important role for government authorities is to provide information so that citizens can voluntarily respond to the pandemic in a way that mitigates their exposure.
Finally, allow us to broaden our perspective after presenting our meta-analysis that focuses on the following question: “What does the evidence tell us about the effects of lockdowns on mortality?” We provide a firm answer to this question: The evidence fails to confirm that lockdowns have a significant effect in reducing COVID-19 mortality. The effect is little to none.
The use of lockdowns is a unique feature of the COVID-19 pandemic. Lockdowns have not been used to such a large extent during any of the pandemics of the past century. However, lockdowns during the initial phase of the COVID-19 pandemic have had devastating effects. They have contributed to reducing economic activity, raising unemployment, reducing schooling, causing political unrest, contributing to domestic violence, and undermining liberal democracy. These costs to society must be compared to the benefits of lockdowns, which our meta-analysis has shown are marginal at best. Such a standard benefit-cost calculation leads to a strong conclusion: lockdowns should be rejected out of hand as a pandemic policy instrument.
I agree wholeheartedly that "one important role for government authorities is to provide information so that citizens can voluntarily respond to the pandemic in a way that mitigates their exposure." I would add that this must include clear, non-alarmist information based on the truth, not on "what we think the public deserves to know"; it must include sufficient information for citizens to make intelligent risk-benefit analyses; and it must not include the stifling of public information-sharing and debate, even at the risk of some of the information being wrong.