It depends what your purpose is.

If you're looking to show whether the spread is overwhelming the capacity of society / the health system to handle it (which is actually the most important thing) then, yes, a population adjustment, absent any other better way, makes sense. https://twitter.com/CT_Bergstrom/status/1249480343968575488

Further, the outbreaks are not coming from a single source in every country, but from multiple as people returned from overseas.

If the number of infected returnees from overseas correlates to your population, then a population adjustment also makes sense.

The real point is ALL these international comparison graphs are basically worthless.

That's because small populations getting overwhelmed by thousands of cases *is* much worse than big countries have thousands of cases https://twitter.com/jburnmurdoch/status/1244380095164420101

The population of Samoa could be wiped out and these goofs would be saying what a good job Samoa did controlling the spread

"My 2-dimensional presentation of a problem with 100 dimensions is the best"