SvennoJ said:
haxxiy said:
Calibrated molecular clocks and genetic analysis indicate all SARS-CoV-2 viral strains descend from the basal types found in Wuhan at the beginning of the year, though, with the earliest possible spread sometime in December (and the virus jumping from animal to human hosts between October and December). Besides, we have data from register offices, adjusted to the day of death, strongly suggesting very rapid spread in the preceding weeks. Bergamo lost 0.4% of its population in a few weeks in March, for instance, with dramatic peaks of abnormal mortality also happening in New York City and Spain soon after.
I think we can confidently argue spread began before everyone was paying attention in a lot of places, but the exceptions like Taiwan and New Zealand would also mean the virus spreading that early wouldn't really make sense in the context of their success. For some reason, the reproduction rate seems just that different from place to place, so there isn't much we can make of it. Why the attack hate was 60% in Bergamo but 10% in Wuhan, for instance?
|
The reproduction rate is indeed very different between areas. It heavily depends on population density, living conditions and cultural differences (hand shake or bow etc). It can spread undetected in the young and healthy (just the flu) until it hits elderly homes and people start dying. The early spread was during flu season, great way for this new virus to hide. Yet reports of strange pneumonia date back to November in Italy, UK and France.
https://news.cgtn.com/news/2020-03-23/Italian-expert-talks-about-strange-pneumonia-cases-in-November-P68sAd0p6o/index.html
https://news.cgtn.com/news/2020-05-08/First-COVID-19-cases-in-France-date-back-to-November-QjPChuck9y/index.html
https://www.nbcnews.com/news/world/new-evidence-race-find-france-s-covid-19-patient-zero-n1207871
|
That much is certainly true, but not to this extent. We have the reproduction numbers from the 2009 Flu pandemic and they didn't differ wildly between countries. It was around 1.2 in Japan and 1.5 in the US, for instance.
As for the latter news, bear in mind that memory can be incredibly unreliable and people have a tendency of confirmation bias (many, many people are retroactively crediting their usual January flu to Covid-19 even thought flu was the more common cause, even for cases with complications, by orders of magnitude back then).
I have seen some arguments about spread in France in late December and early January (specially around Alsace) but, as far as I know, any claim of putative earlier cases haven't been confirmed or reviewed by other researchers. Of course, though, the media loves to report in that sort of speculation.
