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Many scientists and public health experts have long said the coronavirus that has caused a global pandemic originated in a marketplace in Wuhan, China. Now, two new studies strengthen that argument.

The original spread of the virus was a one-two punch, the studies found. Twice, the virus jumped from animals to humans. Virus genetics and outbreak modeling in one study revealed two strains released a few weeks apart in November and December 2019.

"Now I realize it sounds like I just said that a once-in-a-generation event happened twice in short succession, and pandemics are indeed rare," Joel O. Wertheim, PhD, said at a briefing sponsored by the American Association for the Advancement of Science.

A unique storm of factors had to be present for the outbreak to blow up into a pandemic: Animals carrying a virus that could spread to humans, close human contact with these animals, and a city large enough for the infection to take off before it could be contained are examples. Head over to WebMD to read the full story.