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Comment by Ozzie_osman | Hacker News Reader

Could partly explain why it seems like covid-19 isn't hitting developing nations as hard. They have more antibodies to other viruses. There's also the theory that the tuberculosis vaccine (mandatory in many developing nations but not in developed ones) helps too, and there are clinical trials going on to confirm that.

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There's an absence of evidence that this is actually true. Tests are in short supply even in places with their own biotech industry; countries which are reliant on importing tests have no accurate picture of what's happening.

Ecuador is an example which has crossed my radar: ~10,000 confirmed cases, but overall death rates are way up and they're digging mass graves.

We would all love to believe that heat and humidity will blunt the spread of this virus, but I'm not seeing nearly as much evidence of that as I would like.

Ecuador is actually one of a very few number of developing nations that doesn't seem to mandate TB immunization. Iran didn't start it until the 1980s.

That said, I agree there is an absence of evidence... It's all speculation at this point.

Most countries don't do TB immunization, they use vaccines only in specifically developing countries. Developed countries use antibiotics generally.

Actually most countries in the world do immunize against TB. And developing countries in particular overwhelmingly do. The US doesn't mandate and most European countries have stopped.

http://www.bcgatlas.org/

An interesting observation about that map is that there is a high correlation between countries that stopped BCG vaccinations and high fatality rate from Covid-19. However, Australia is one of the countries that stopped doing BCG vaccinations but it does not have the high fatality rate of western European countries. What's going on there?

Idk. There's so many confounding factors. I don't know when they stopped the vaccination, but maybe it was recent enough that the vulnerable (elderly) did actually receive the vaccination? Maybe temperature does matter. Maybe they're just behind on the curve. We can only wait and see as more clinical data becomes available.

That may be true today but in the past, not so much. E.g. BCG was given to all non-reactive children in the UK between 1953 and 2008.

My impression is that it's being attributed to the smaller international travel to Africa in the first place, and then that all stopping when the rest of the world locked down. There are some pretty wrenching predictions for how they'll go when it does start spreading, if that's correct.

It's also warm and wet in many developing nations. Seen a couple pieces suggesting COVID is relatively heat-phobic.

Would also jive with seasonality of the flu...

That idea of flu season seems a distinctly North American notion. Flu season in Thailand is June to October, which coincides with rainy season when it is hot and very wet.

I graphed death rate by absolute latitude for countries with more than 1000 cases, and there is a clear trend. There is a bulge in the middle latitudes, and dips toward the lower and higher latitudes. My guess is the virus doesn't do well in hot climates, and people don't congregate much in very cold climates.

It’s the spring in the northern hemisphere, it’s not cold anywhere in the US or Europe. I don’t see how your conclusion is relevant

Yup not cold at all here in Indiana. Please disregard the snow that we had earlier this week...

Lol. It's quite difficult (misguided) to generalize about an entire country!

Sounds plausible. It may be premature to assess the relative impact of covid-19 in those nations. Hopefully you're on to something though...

I don't buy the BCG thing. For one, they count France as one of the countries that don't vaccine and where covid-19 is hitting hard. While the latter is true, the former is... only technically true now. France stopped vaccination, but it was mandatory for school children between 1950 and 2007. So people up to 80 or probably more are vaccinated.

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