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Comment by garyclarke27 | Hacker News Reader

Poor article, not even a single mention of the most likely reason for low death rate (apart from young population), the weather! Strong Sun (UV light) and high humidity quickly kills the virus. Warm countries like Thailand - despite millions of tourists from Wuhan - have low death rates. In Spain cold Madrid was affected much worse than sunnier south. Summer will soon rapidly kill of the virus in southern Europe.

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Plenty of warm areas are being hit hard, but a lot of warm countries have "reporting issues" (look at the excess deaths in Jakarta for an example). Heat might lower R0 by some amount but it's still way above 1 without measures

There's also strong correlation inside the same countries regarding the more sun = less deaths vs less sun = more deaths. The best examples that I can give are Italy, where Rome and everything South of of it has ridden the pandemic wave pretty ok (with the slight exception of the region of Puglia) and Spain, where the region of Andalusia in the South has had only a 5% or so excess in the number of deaths for this year

It is possible the correlation is: more outdoors -> less deaths

Where the relationship with "more outdoors" is kinda temperature dependent (not too cold nor too hot) and culturally/regionally dependent

In Brazil the correlation is going almost perfectly as more sun = more deaths.

From the article: "Yet others talk about the possibilities of the presence of a less virulent strain of the virus in India, along with the possibility that its hot weather was diminishing the contagion. Both these claims are not backed by any evidence."

> "Both these claims are not backed by any evidence"

There is evidence for the weather claim, but it's complicated by other factors.

Multiple studies [1] have observed a correlation between weather/UV and severity of outbreak.

Wuhan, Milan, Madrid, Qom, UK, Korea and Northern USA have all fit a comparable weather profile during their outbreaks.

The problem is that this virus seems to be more durable/resilient than other seasonal viruses (flu, common cold), and even in hot climates, many people still spend a lot of time congregated in air conditioned office/residential buildings, shopping centres, public transportation systems, etc.

So it's true that hot weather alone is not enough to end an outbreak.

But it can reduce the extent/severity, and the observed evidence seems to bear that out.

[1] https://www.ft.com/content/c8ed3692-6db3-11ea-9bca-bf503995c...

Yeah. And yet...

- The statistics indicate the contagion is diminished.

- No one knows why.

- Someone posits a plausible explanation of an effect seen in some (but not all) similar viruses.

- Explanation is dismissed without consideration, and the working theory us that the statistics are wrong.

Seems strange given the fact that I've seen numerous academic papers shared over the last few months indicating that hot weather and high humidity do indeed have some kind of effect on the virus's transmission.

It doesn't "kill the virus". It reduces the half life of the virus, thereby reducing the time it has to spread from surfaces. This means the virus is less transmissible.

That alone cannot explain why deaths / infections ratio is low in India compared to the west. There are many hypothesis: - Higher testing in India - BCG vaccine immunity. None of these have been scientifically validated yet.

And then summer ends and fall begins and we start all over again. Only longer, this time.

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