My two worries are:
– That this correlation is do a large extent due to the very limited testing in poor countries.
– That this correlation will soon be the other way around and poor countries will have the highest rate of cases.

[source: http://ourworldindata.org/coronavirus-data]">https://ourworldindata.org/coronavir...

For the second worry one point to consider is the very strong correlation between GDP per capita and the disease burden from infectious diseases – shown in red in the chart below.

[from our paper https://academic.oup.com/heapol/article/33/suppl_1/i14/2996762]">https://academic.oup.com/heapol/ar...

For the other point – testing is often low in poor countries – you can explore our dataset on COVID-19 testing here http://ourworldindata.org/covid-testing 

Here">https://ourworldindata.org/covid-tes... is a comparison of the testing rate across some countries.