arjun2761 wrote: ↑Wed Jun 24, 2020 8:41 pmAlso, agree that a significant part of India isn't exposed as you state. But even if 75% of India isn't exposed, the Indian tests per million of around 5000 is far below the 80000-100,000+ of the developed nations. That is, even if we consider our exposed population base to be 25%, our tests per million for the exposed population would be around 20000 which is a factor of 4 less than the developed countries.
Actually I didn't say that 75 percent are exposed. I only said (my guess) that perhaps 75% don't have anybody within 5 km radius with infection.
I don't have an easy index to use to figure out "what population" should be used as the divisor for the tests/million stat. I just don't know. Some indicator is needed on the extent of the spread of the disease, as it takes time to get to different places. Places like Bihar, Odisha, Goa, Tripura etc almost had NO cases at all till about 6 weeks ago. Just did not!! No doctor reported anything, no patient told any reporter, no rumors, nothing. So there was no point in using their population in the divisor.
It may only be a month or two for a small European country to have the disease get to every neighborhood (or to 95% of 10 sq km areas, or 95 percent of all 1000-people population groups) in the country, but it is taking much longer for the US or Russia or India.
I just know that India has vast stretches and so many cities with more than 500K population where there aren't even 250 cases. You won't find that anywhere else in the world right now (except in China, for whom nobody has reliable numbers). I mean, which country has a city like Coimbatore or Gwalior with over a million population that still has only 300 cases? And even those cases were all mostly Tablighi JamaAt people or migrant travelers who were traced, put in quarantine, and recovered long ago (and not any community transmission growth from seed index cases). The test positivity in those places are like less than 1 percent in the test they have done, so it is not due to lack of testing there. Maybe at some point Coimbatore will start a growth like Madurai did this week.
A couple of months or even a few weeks seems to have been enough for it to get to every place in other countries, but that has not been the case in India. This was also because of an extremely early lockdown and the total shutdown of intra-nation travel. So the spread has been basically in some limited areas of India. Even after that, it is only slowly getting to new towns and starting. So, again, the problem is that spreading of the disease takes time. Until then, adding every place's population makes no sense.
I can imagine the tests/million stat becoming meaningful, maybe, once the spread can be assumed "complete". Maybe one indication would be the cumulative tested cases' total showing an inflection point (ie, the second derivative becomes negative, or daily additions dropping). That may be an indication of the spread being "complete" and comparable to another part of the world. But if there is a second wave in the total, that indicates that the spread was not complete initially - and then you have to throw out the earlier inflection point and wait for the next. There could also be a third wave if it gets to some other part and starts growing... then you wait for a third inflection point! US, for instance now have to wait till we get the inflection point once CA, TX, FL calm down. The tests per million in the US is also an erroneous measure.
Right now, Mumbai maybe the only place where tests per million would make any sense, because only Mumbai has shown in inflection point. But it is possible that there areas of Mumbai that will grow later and we might need to wait for a second inflection point to be sure that those areas; population needed to be in the divisor.
Hope I make some sense in what I am saying.
But test positivity is a comparable measure across countries. It just says something about whether you are getting to the places where you need to test.