The fight against coronavirus will not be won until every country in the world can control the disease. But not every country has the same ability to protect people.

For low-income countries that struggle with weak health systems, large populations of impoverished people and crowded megacities, "there needs to be a very major adaptation" to the established measures we've been using to fight COVID-19, says Dr. Wafaa El-Sadr, an epidemiologist and director of ICAP, a global health organization at Columbia University. 

The COVID-19 playbook that wealthy nations in Europe, Asia and North America have come to know — stay home as much as possible, keep a six-foot distance from others, wash hands often — will be nearly impossible to follow in much of the developing world.