The title is self-explanatory and obvious for anyone who looks at case charts. I would encourage you to look at California in particular, which has been stringently locked down for a long time. But here is some research on the topic as well.
This paper comes from a part of Denmark. (Medrxiv Paper) This area had a lockdown in November due to concerns about mutations found in CV-19 in mink. Other areas of Denmark had no similar restrictions. While cases fell in the area studied they also fell in the other parts of Denmark and were declining before the restrictions were imposed. The authors’ conclusion is that voluntary behavior changes were likely adequate and that the effectiveness of lockdowns has been overstated.
This paper from the National Bureau of Economic Research finds that the loss of jobs accompanying the lockdown restrictions will have a substantial effect on health in future years. (NBER Paper) Building on previous research showing that employment losses, during recessions for example, increase mortality and decrease life expectancy, the authors estimate that the CV-19 lockdown-induced loss of jobs is a shock 2 to 5 times larger than the typical one and will have a correspondingly greater effect on mortality. They estimate that an additional 890,000 deaths will occur over the next 15 years. I believe that will be substantially more deaths than CV-19 actually caused, but because these people won’t have CV-19, they don’t count. The impact, as you would expect, will be greatest among minorities.
And another study from the NBER focuses on deaths of despair. These also stem from lockdowns and the accompanying terrorization campaign. (NBER Paper) The authors attempted to identify excess deaths, both from CV-19 and from other causes, during the epidemic, by age group. They found at least 30,000 non-CV-19 deaths, primarily among young and middle-aged men, with a focus on opioid mortality. That is a lot of lost years of life.