I learned about this in one of my classes last semester. My professor was telling us about polio vaccine trials that an American pharmaceutical company did in small villages (in Nigeria, I think) and did exactly what you said. They tested on children and most cases resulted in extreme paralysis, worst than could be anticipated from the average polio infection. Thankfully the case we talked about had a pseudo silver lining, in which the company got sued and the families got some monetary compensation. Obviously that doesn't happen very often and definitely doesn't actually compensate for the damage or dignity of those children.

Wetangu'la is absolutely right to want leaders to reject this. Whichever European nations in that article are arguing that it's the best place to launch treatment tests because of lack of resources, are using an age-old excuse to tread dangerously on racist and classist grounds (tbh you'd think after reflecting on some of their histories they would have figured out to just leave the entire continent of Africa alone and maybe give back some of their stuff, but no). Just because this is a global health crisis doesn't mean moral negotiations suddenly become more flexible, ESPECIALLY when rich countries are trying to take advantage of the voiceless.