that seems to imply that developing countries had lower survival rates, despite their more favourable demographics, which would be sad.
This isn’t impossible because there seems to be a correlation where people with lower socioeconomic status have worse Covid outcomes, but I still doubt that the IFR was worse overall in developing countries. The demographics (esp. the proportion of people age 70-80, and older) make a huge difference.
But I never looked into this in detail, and my impression was also that for a long time at least, there wasn’t any reliable data.
From excess deaths in some locations, such as Guayaquil (Ecuador), one could rule out the possibility that the IFR in developing countries was incredibly low (it would have been at least 0.3% given plausible assumptions about the outbreak there, and possibly a lot higher).