People are talking about “the lost year”. Based on that premise (which clearly isn’t correct), let’s do some simple math: Let’s say half of the world’s population had to change their lives drastically for a, per individual combined, period of 3 months. Let’s also assume the 7.7 billion estimate for the world population is correct, and that 71 years is a reasonable life expectancy estimate (as per wikipedia):
7 700 000 000 * .5 * 3 = 11 550 000 000 months lost
11 550 000 000 / 12 = 962 500 000 years lost
962 500 000 / 71 = 13 556 338 people lives lost
As of today, the WHO estimates 1.69 million people died of COVID-19.