https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v2.full.pdf
"HCoV-19 remained viable in aerosols throughout the duration of our experiment (3 hours) with a reduction in infectious titer from 103.5 to 102.7 TCID50/L, similar to the reduction observed for SARS-CoV-1, from 104.3 to 103.5 TCID50/mL (Figure 1A). HCoV-19 was most stable on plastic and stainless steel and viable virus could be detected up to 72 hours post application (Figure 1A), though the virus titer was greatly reduced (plastic from 103.7 to 100.6 TCID50/mL after 72 hours, stainless steel from 103.7 to 100.6 TCID50/mL after 48 hours). SARS-CoV-1 had similar stability kinetics (polypropylene from 103.4 to 100.7 TCID50/mL after 72 hours, stainless steel from 103.6 to 100.6 TCID50/mL after 48 hours). No viable virus could be measured after 4 hours on copper for HCoV-19 and 8 hours for SARS-CoV-1, or after 24 hours on cardboard for HCoV-19 and 8 hours for 39 SARS-CoV-1 (Figure 1A)."
and then this:
What I find interesting about this is that COVID-19 behaves very similarly to SARS - especially "This indicates that differences in the epidemiology of these viruses likely arise from other factors, including high viral loads in the upper respiratory tract and the potential for individuals infected with HCoV-19 to shed and transmit the virus while asymptomatic"
What I find interesting about this is that COVID-19 behaves very similarly to SARS - especially "This indicates that differences in the epidemiology of these viruses likely arise from other factors, including high viral loads in the upper respiratory tract and the potential for individuals infected with HCoV-19 to shed and transmit the virus while asymptomatic"
High viral loads (1,000 to 10,000 times that of SARS even just after onset of symptoms) and viral replication in the upper respiratory tract (unlike SARS) were confirmed in this German study.
This European study estimates that the mean generation interval (time for one generation of the virus' hosts to infect the next) was 5.20 days in Singapore and only 3.95 days in Tianjin, China.
The European study also estimates the presymptomatic transmission rate to be between 44 and 75% of total transmissions. (!)
So aggressive social distancing to lower the spike of cases makes a lot of sense, given that these results suggest high contagiousness and a large amount of presymptomatic spread.
One question is why COVID-19 is not even worse than it is, given these results and those of the paper in the URL copied from the earlier post.
Seems likely that the number of mild untested cases is either significantly underestimated and some "herd immunity" is developing, or that some fraction of the population already has some immunity, as suggested by the cruise ship quarantines (where less caught it than the 60 or 70% or more which might be needed for herd immunity to have a significant effect). (Maybe a combination of these effects could be reducing the total spread too.)
Bottom line, COVID-19 is hardly the end of the world, but slowing the spread will prevent some deaths (from COVID-19 and from other conditions properly treatable only if the hospital system is not overrun) and is thus worth some pain.