Printing money causes "inflation" [1]. This effect is lessened in chronically-low inflation environments (like our current one) [2]. In situations where demand

Printing money causes "inflation" [1]. This effect is lessened in chronically-low inflation environments (like our current one) [2]. In situations where demand is artificially low (like lockdown), and therefore will broadly bounce back when allowed to, you can print a lot without that inflation [3]. [1] = Printing money creates additional dollars in circulation without increasing the supply of goods those dollars are chasing. If you imagine adding a zero to every dollar simultaneously (aka 10x the money supply), without actually creating anything new, after a brief period of adjustment all goods would essentially just add a zero onto their cost to find equilibrium. This is "inflation" in effect. In practice though, people tend to just print 1.1x what they printed yesterday ad infinitum, and so this effect compounds (aka "runaway inflation") and you end up like Zimbabwe with wheelbarrows full of worthless cash. [2] = Currently, price rises (relative to a dollar) have been steady in aggregate, aka "chronic low inflation". This is a subject of economic debate as to why, but suffice it to say that is where we are and thus there appears to be "slack" in the currency to print a little more without runaway inflation. [3] = Usually demand suffers a sort of chronic shock as part of a recession or depression. In these cases you can expect it to be depressed next year too, which means investment is useless and thus the cycle of depression lasts and causes a feedback loop. In such a situation, printing additional cash is very inflationary because the supply of goods being sought by those additional dollars is depressed and the supply chains and required demand to justify creating them is not there. In today's world the US economy was broadly fantastic until five minutes ago, and provided this lockdown doesn't last too much longer (flushing out a lot of small business and causing cascading failure), the underlying conditions will remain ripe for growth soon, and thus the newly-printed dollars can reliably chase future goods that are forthcoming.