Very hot countries have it easier to do contact-tracing. It’s plausible that the virus deactivates at 30 degrees Celsius (I think I may have read that in the often-cited Lipsitch article). In the hottest countries, public transport can be 30+ degrees and even grocery stores can be that warm. If infections happen primarily in indoor settings (e.g., business contacts or partying or household), contact tracing is easier, giving hot countries an initial advantage at preventing outbreaks early on. However, once contact tracing fails, that advantage shrinks. What remains is only that the r0 is lowered somewhat by heat interrupting certain types of of transmissions, but not all types. It wouldn’t surprise me therefore if hotter countries also need extreme measures to contain the case count from growing exponentionally, even if the doubling time might be generally lower for hot countries.
Another hypothesis:
Very hot countries have it easier to do contact-tracing. It’s plausible that the virus deactivates at 30 degrees Celsius (I think I may have read that in the often-cited Lipsitch article). In the hottest countries, public transport can be 30+ degrees and even grocery stores can be that warm. If infections happen primarily in indoor settings (e.g., business contacts or partying or household), contact tracing is easier, giving hot countries an initial advantage at preventing outbreaks early on. However, once contact tracing fails, that advantage shrinks. What remains is only that the r0 is lowered somewhat by heat interrupting certain types of of transmissions, but not all types. It wouldn’t surprise me therefore if hotter countries also need extreme measures to contain the case count from growing exponentionally, even if the doubling time might be generally lower for hot countries.