Researchers from the Pasteur Institute (yes in France) sampled living bats in Southern China and Laos and sequenced all their corona viruses. Just about every segment of SARS-COV2 RNA was found in one or more of those 15 wild viruses. Recombination happens all the time in these bat corona viruses, and they figured out the five recombinations needed to make SARS-COV2. They have not found one bat with SARS-COV2, but they have found all the parts needed to make it. That's probably because they only sampled a few of the millions of bats living there.

TWIV reviewed an interesting paper investigating the origins of the outbreak. It probably happened when an infected racoon-dog was brought to the live animal market. Then it spilled over into a human and went community-wide. Lots of the first found cases were connected to the market, but since so many cases were asymptomatic, the first hospitalized case noticed in early December was not the real spillover case. Or it might have spilled over into a hunter or animal transporter that got it to the market.

Spillovers happen when a human gets infected with an animal virus, and then a small mutation makes the new variant much better adapted to human-to-human transmission. We know corona viruses mutate often because RNA replication is subject to so many errors. I heard it may require over 500 replications just to get a single unmodified copy! That means SARS-COV2 mutates all the time, but almost all new variants are garbage.

Educating anyone benefits everyone.