I don't know where to post this , as it's mostly
boring scientific insights regarding SARSCov2 , and this thread is about sharing thoughts and feelings about it , so I am sorry for polluting this thread :)
the novel coronavirus could persist as aerosols—tiny airborne particles—for up to three hours, though Morris clarifies larger respiratory droplets are more likely to be infectious. Viral aerosols are primarily a concern in clinical settings where certain treatments like ventilation can produce these particles. It is unlikely that these coronavirus aerosols come into play in open-air settings or public places like supermarkets.
This is , however , not particularly new or alarming:
Viral RNA was identified from respiratory droplets and aerosols for all three viruses, including 30%, 26% and 28% of respiratory droplets and 40%, 35% and 56% of aerosols collected from coronavirus, influenza virus and rhinovirus-infected participants, respectively
The study also revealed the novel coronavirus and its cousin SARS, which caused a major outbreak in 2002 and 2003, last on surfaces for similar amounts of time.
So it's not more persistent or durable outside the body . Question remains: what makes it more infectious?
The average number of viral particles needed to establish an infection is known as the infectious dose. We don't know what this is for covid-19 yet, but given how rapidly the disease is spreading, it is likely to be relatively low – in the region of a few hundred or thousand particles, says Willem van Schaik at the University of Birmingham, UK.
This is , however , just a speculation . Others were raised as well:
The previous SARS Cov1 and the present SARS CoV2 use the same "receptor" to enter cells and the suggestion is that SARS CoV2 is just more efficient in using the "entry door" into the lung cells
As for viral load , it does not mean you're more ill :
Health workers investigating the covid-19 outbreak in the Lombardy region of Italy looked at more than 5,000 infected people and found no difference in viral load between those with symptoms and those without.
Which is unique .
If the initial amount of virus a person is infected by doesn't correlate with the severity of disease symptoms, this would mark covid-19 out as different from influenza, MERS and SARS.
However it does mean you're more infectious to others.
If you have a high viral load, you are more likely to infect other people, because you may be shedding more virus particles.
And this is one of the main reasons it spreads so quick.
Incubation period: time between infection and symptoms.
Shedding: expression of virus from host to environment. (basically becoming infectious)
The viral load is very high in the throat and early on. This helps to explain why the virus is so infectious; it can be transmitted by droplets from the upper respiratory tract, before people may be aware that they have an infection.
high levels of virus replication in the upper respiratory tract early in the course of infection, and highlights the efficient transmission of virus infection when symptoms are mild. Prolonged virus shedding in sputum is observed
This is unlike Ebola , for example , which is not infectious during incubation .
Questions about COVID-19 and viral load -- describes immune response (inflammation vs. antibodies) , and the significance of high/rapid viral load.
In some grotesque sense this virus found the '
sweet spot' : as infectious as SARS-1 , but not as deadly .
(right in the middle: 10 times less fatal than SARS1, but 10 times deadlier than flu)
Most of the information here was known , published , researched or discussed before March 1 , and at most by March 15 -- so it's not very "new" .
Sadly , during that time , when these things were known , WHO published misleading (though not false) statements:
This means that influenza can spread faster than COVID-19
Transmission of the virus before the appearance of symptoms is a major driver of transmission for influenza. In contrast, while we are learning that there are people who can shed COVID-19 virus 24-48 hours prior to symptom onset, this does not appear to be a major driver of transmission.
No , idiots , around 50% of people were shedding without any symptoms ... And this was known.
(50% asymptomatic + 30% mild = 80% non-hospitalized)
This is a question of numbers and threshold , and interestingly there is always influenza around us (hence the importance of viral load):
Influenza is one of the most contagious and rapidly spreading infectious diseases and an important global cause of hospital admissions and mortality. There are some amounts of the virus in the air constantly. These amounts is generally not enough to cause disease in people, due to infection prevention by healthy immune systems. However, at a higher concentration of the airborne virus, the risk of human infection increases dramatically.
There were 3 influenza pandemics: 1918, 1957, and 1968 , all 3 different antigenic subtypes of influenza type A virus: H1N1, H2N2, and H3N2 respectively . (type-> subtype -> linease -> strain -> isolate) . Each of these pandemics had at least 2-3 successive waves -- and an increase in the case-fatality rate in the later waves . This does not mean SARS-2 will act the same , but it's interesting to see .
TLDR: Asymptomatic shedding with high viral load
cc: @Underscore 
