Coronavirus (COVID-19) Discussion Thread

[SvennoJ]

haxxiy said:

SvennoJ said:

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.

https://www.bbc.com/news/world-europe-52526554

A patient treated in a hospital near Paris on 27 December for suspected pneumonia actually had the coronavirus, his doctor has said. This means the virus may have arrived in Europe almost a month earlier than previously thought. Dr Yves Cohen said a swab taken at the time was recently tested, and came back positive for Covid-19. The patient, who has since recovered, said he had no idea where he caught the virus as he had not travelled abroad.

Pretty convincing argument, community spread before December 27th. Since that person already had symptoms bad enough to go to the hospital, infection was likely already mid December.

The November ones are less clear since it's from looking at hundreds of x-rays finding particular symptoms that look like what covid19 does to the lungs. The flu varies between years and places, who knows a mild flu season was disguising the onset of the covid19 pandemic. It didn't need to be that mild anyway, the early numbers are quite low. 2 cases in November means 120 cases a month later with R0 at 2.0. With a fatality rate of 1%, easily missed. If early transmission is as low as R0 1.5, from for example healthy young athletes bringing it back to France start of November (thus many asymptomatic cases) then 5 infected people bringing it back early November turn into 50 by early December, 500 by early Januari. Until it hits more at risk people who get really sick, nobody would think much of it.

I think the confirmation bias lies more towards the "it's just a bad flu". There are many more mild cases and cases without symptoms.

It's plausible, and a better explanation imo than the virus suddenly speeding up to get the explosive growth early March. And it's good to know what the actual infection rate is to better understand how to stay below R 1 with the least destructive measures. Atm it seems everyone is still doing trial and error with enormous lag from testing, mostly only after people show symptoms.