Thread by @VincentRK

@sumanthraman @EricTopol This is a great question. I’ll try my best to answer.
1) First is that the question also applies to Europe which is doing just as bad as the US. So why are USA and Europe doing worse than more crowded and much poorer countries?

@sumanthraman @EricTopol 2) I think one of the most likely factors is that there must be some form of pre-existing cross reactive immunity which is helping keep the disease severity low. So more asymptomatic cases, and fewer hospitalizations and deaths. I did a thread on this a while back.

https://twitter.com/vincentrk/status/1296404093343326209

@sumanthraman @EricTopol 3) The second factor is certain favorable demographics in countries like India: age distribution (lower median age), and lower prevalence of obesity. A lot of severe COVID is associated with these two factors.

@sumanthraman @EricTopol 4) Third is that mild cases of COVID are not likely being captured in India. So I think it’s hard to compare the case numbers. But it’s hard to hide overflowing ICUs or deaths. And so there is no question your observation is right; India has much less of severe COVID than the US.

@sumanthraman @EricTopol So some countries have done well due to doing everything right (S. Korea), some with great border control (New Zealand). Some have avoided high levels of deaths and severe COVID because of some protective factors: preexisting immunity, lower age, lower obesity rates.

@sumanthraman @EricTopol On another note, keep in mind u can only get COVID for someone with COVID. So some countries including crowded ones have successfully made COVID an external threat by test/trace/quarantine ALL internal cases with simultaneous strict border control to keep new cases from entering.

@sumanthraman @EricTopol Once you do that people can be packed in crowded areas and go mask free because there is no COVID around to get COVID.