I didn't really answer the isolationism point, apologies.  I agree.

There is no doubt governments have a role in massive events, and that the public actually wants them to 'do something'.

In 2008/2009 the G20 was formed by Gordon Brown to actually act in a coordinated way and deal decisively with what was a serious credit crunch. It worked.  The lack of of a similar consensus and coordination this time around however, is plain and could get risky.  

In a world crisis it is risky to go it alone, or just blame someone else.  This attitude seems to be hard-written into the current zeitgeist.  The virus will be beaten, but the economic hit /recession will not be beaten easily if there is a credit crunch. This is about debt not being honoured and borrowing not being available because of a failing of trust.

If even a small country's banks get in trouble, and those banks can't be bailed out with loans, because no one will lend to them for fear of default - there will be trouble.   This is when a 'go it alone;' strategy will collapse; as with countries defaulting, then so will global demand.  This and its subsequent 'domino effect' could be a fire storm that will cause far more pain than the virus.  

The virus is just the straw. The camel's back is the world economy.

Edited. I often do.