Why do these viruses often appear in China first? Has there been any study to find out any common patterns? Is it the food? Culture? Living environment?
One possible reason for delayed virus detection in the West is our sluggish response to identifying new strains (in some of our largest countries, not all). But I think the emergence and spread of serious viral infections is largely influenced by population density, rather than geographical location. And the population density in China has gone up a lot in about the last decade, making more serious transmissible diseases come out of China recently.
When Covid's first wave saw exponential infection growth, statistics and graphs demonstrated striking similarities among urban areas worldwide. In contrast, rural regions consistently exhibited lower infection rates throughout the pandemic.
To illustrate this with a personal anecdote, I know someone who lives in a tiny village on a ranch (population: ~30), and they have reported seeing zero Covid cases, having interacted with around 50 other people over the last four years. I think this underscores the role of population density in virus transmission.
People in China also interact more closely with animals, and with a wider variety, than in the West. The West does not have any wet markets or nor the wide variety of species available for consumption. This helps in the virus jumping species. Once it jumps, the population density helps it spread.
Once or twice, although it wasn't a major sort of fair. There were a lot of animals, and now that I think about it, quite a wide variety of chickens. But it's only a few weeks out of the year, and in summer. And not very much blood. (Don't know if blood makes a difference in this case, though) I'm still a little shocked by the (large) fish gills I saw hanging up on a wall in a market in Hong Kong some years ago, looked like it was still breathing.
When I visited South China, everything was crowded. Sick building syndrome is probably more common due to the common use of AC and large shopping malls people hang out at as well as recirculating air. My friend in India said that she did not get constant electricity in Gujarat so AC wasn't as common everywhere.
China is much more urbanized, India's population is still majority rural. And China also has a more robust public health system, which means that more cases get detected in the first place.
Maybe Indians have less contact with wildlife (due to different settlement patterns, or religious or cultural restrictions on eating wild animals?), or less average physical mobility (more expensive and inconvenient long-distance transportation), or a climate less conducive to certain modes of virus transmission?
A smaller fraction of the population working or commuting in huge indoor spaces?
Maybe (contrary to Americans' intuition) Chinese public health surveillance is both more effective and more transparent than Indian, leading to a measurement bias because some disease outbreaks that arise in China get better-documented?
The viral jump from animals to humans is a common mechanism in many of the worst pandemics, with covid-19 and hiv being prime recent examples. There's some evidence "the spanish flu" of 1918 came from swine.
If I were working on the problem "how can we reduce the frequency new very dangerous viruses are introduced" I would pay attention to this aspect.
The solution to this problem is the same as nearly every other problem humans create: stop destroying ecosystems and animal habitats, stop expansion, reduce meat eating, etc. These things increase the transmission of zoonotic diseases. There was a really good article in 2020 that I can now not find where an expert discussed how these things are not new, COVID was not a surprise, and that these transmissions will do nothing but increase in frequency if we don't systematically tackle these problems.
I thought the most likely origin of Covid-19 is a lab leak (at least according to the latest from the DOE and the FBI), likely from gain-of-function research gone wrong?
No – even that DOE report gave it a low probability ranking. It’s perfect for conspiracy mongers because you can’t completely rule out the possibility but the evidence has pretty consistently pointed at a non-lab jump, possibly in the wet market, and that’s not surprising since it’s a common scenario scientists have been warning about for decades.
> even that DOE report gave it a low probability ranking
Well, specifically, they assessed with "low confidence" that the "most likely" source was a lab leak. Meaning they think the wet market theory is less likely, though also with low confidence.
I do note in the analysis you linked that the authors admit to unusual circumstances around the data they used, and that the source of the data is the Chinese CDC. Given the obvious incentive on the part of the Chinese government to disclaim a lab leak, I'm hesitant to take this as conclusive evidence.
When Covid's first wave saw exponential infection growth, statistics and graphs demonstrated striking similarities among urban areas worldwide. In contrast, rural regions consistently exhibited lower infection rates throughout the pandemic.
To illustrate this with a personal anecdote, I know someone who lives in a tiny village on a ranch (population: ~30), and they have reported seeing zero Covid cases, having interacted with around 50 other people over the last four years. I think this underscores the role of population density in virus transmission.