A couple notes on this:

- Right now, there's some ongoing research about R0 relative to humidity, and it's not promising. This includes Singapore, but it should also be noted that Singapore has an amazing public health system that will confound using it as an example in both directions.

- Having written a review on the seasonality of influenza, the fact of the matter is we have very little notion of why it's seasonal, and a lot of "just so" stories.

Can you point me to your review?

A few years ago (circa 2010 or so) when I was seriously working on epidemic modeling, we tried to look for an effective seasonality model, based on temperature, humidity, etc that worked globally and failed miserably. What seemed to work in one country or area failed completely in others, and vice versa. I'm curious to see if things have improved since then

It's an older paper (circa 2006) but...to be honest, I revisit it occasionally, and the problems we point out are still there. https://jvi.asm.org/content/81/11/5429

Ahahahahah... HN really is a small world. I remember this paper. The section on “indoor heating and AC” stuck to my memory to this day. Back then we were hoping for a seasonality-based follow up to this paper: https://www.pnas.org/content/106/51/21484 but it was not meant to be.

Seasonality is a...vexing problem. It seems to straight forward, and then...

> Having written a review on the seasonality of influenza

Is one of the theories lack of Vitamin D?

Yet miami has the same flu season as Minnesota. AFAIK.

Yep.

Singapore is having 30ºC days, yet the epidemic is progressing and the city is already bracing for the worse...

"warm weather may have an effect on transmission" and "a warm city is dealing with infections" are not mutually exclusive statements.

And for the record, as of a little over a week ago, there were only a dozen cases in Singapore according to the WHO. Even if they were mutually exclusive, Singapore isn't exactly the best example.

https://www.who.int/docs/default-source/coronaviruse/situati...

As of yesterday it’s 47 cases in Singapore.

https://www.moh.gov.sg/2019-ncov-wuhan

22 of these were traveling straight from Wuhan.

Hm, increasing 47/12 in 7 days is the same as doubling every 3.55 days.

Some involve evacuated individuals from Wuhan so its actually a slower growth rate

Singapore also has a lot of air conditioning. Perhaps the transmission is occurring primarily indoors, away from the 30ºC heat.

Exactly. The comparison with Indonesia is interesting, which has a similar climate, but isn't as rich or developed as Singapore.

Air conditioning is actually very conducive to colds and the like. When you go from outside to inside you're usually sweaty and the air conditioning tends to make you too cold until you dry out. I've caught way more sniffles in the tropics than in the freezing climates.

Anecdotally, I flew from Bali to Singapore today and there seemed to be a lot more sniffles and coughing in Singapore. In Bali the architecture is very open with lots of fresh air, scooters being popular for transport whereas in Singapore they tend more to sitting together in air conditioned boxes of various types (buildings, busses etc).

The primary means of getting around in Singapore is public transportation (bus, train).

Public transit in SG is heavily air conditioned.

Air-conditioning also removes humidity from the air.

On a tangent, I'd love to see a graph of illnesses during summer before / after the widespread adoption of AC.

Someone could do a study of schools with broken ACs. That might be an easy way to study it.

I don't think a school would operate with broken AC

At least in the US plenty of schools in hot climates do not have A/C.

https://www.the74million.org/article/exclusive-too-hot-to-le...

Even those that do have A/C don't cancel class when it breaks.

https://www.floridatoday.com/story/news/education/2019/09/11...

The real takeaway from the 74 Million piece is that information about HVAC in American schools is difficult to come by. It would certainly be interesting to look at COVID-19 in schools vis-a-vis A/C, but good luck prying information from the school districts about either infections or air conditioning. Perhaps it would be easier in a tropical country like SG where A/C is more of a necessity than a luxury.

Most public schools in Singapore don't have A/C in most of their classrooms.

And circulated through the building via blowers.

maybe it could have been much worse if it was colder.

Also the coronavirus doesn’t really seem present in countries in the Southern Hemisphere except for some imported cases in Australia. There’s nothing being heard of South America or Africa which could be because of their hot climate.

Do many people from those areas travel to China compared to places where the coronavirus?

Hopefully the novel part isn't that it acts like the Spanish flu and thrives just as well in the spring and summer and lasts years.