I can’t be bothered to wade through that entire PNAS paper, but it’s very unclear to me what exactly this could mean. Life expectancy for who, exactly? The abstract and a table halfway through say they are talking about life expectancy at birth. I don’t see how they could possibly make any reliable inference about the effect of COVID on life expectancy for someone born today, but surely there’s a good chance that it’s negligible once we have vaccines and herd immunity.