We know that recessions cost lives. One study (published in The Lancet, so worth taking a second look at) suggested 500k excess cancer deaths from the global financial crisis[1], and another study (published in the BMJ) suggested that excess suicides in 2009 alone across the US and 53 other countries totalled some 5k[2]. I don't know of a single comprehensive effort, but we know recessions reduce the resources available at the margins for food, medicine and shelter, and increase the suicide rate. The net effect for something like the GFC seems likely to be on the order of tens of thousands of deaths (and perhaps significantly higher), and the recession caused in part by Covid-19 and in part by our reaction to Covid-19 seems to be within an order of magnitude of the GFC.
Thus, it seems fairly obvious that at least some responses to Covid-19 would cost more lives than they saved. If you're evaluating a measure that, let's say, would save X lives from Covid-19, but would cause the resulting recession to go from, Y% as bad as the GFC to Z% as bad as the GFC, there are absolutely values for X, Y and Z which would make the measure net negative on lives.
I'd be happier if that tradeoff got acknowledged a bit more often, even in a perfunctory "well, we're clearly MILES away from the break even point, so let's ignore it" sort of way. If you pretend that tradeoffs don't exist, you're unlikely to reach an optimal decision.
[1]: https://www.telegraph.co.uk/news/2016/05/25/financial-crisis...