How Is It Spreading

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  • Thu, Mar 26, 2020 - 02:22am

    #1
    matfax

    matfax

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    How Is It Spreading

Countries with wide-spread masks use such as South Korea seem to have the virus under control. South Korea should have <1k cases in ca. one month. The number of active infections keeps declining steadily there. Looking at the Italian numbers though, it’s obvious that nationwide quarantine measures don’t seem to have any significant effect. Italy’s nationwide quarantine is in effect since March 9th. In contrast to South Korea, the R0 hasn’t decreased below 1. It’s rather leveling around 1. The virus is still spreading in Europe.

The only differences between Asia and Europe are (1) different ethnicities, (2) different virus strains, (3) wide-spread mask usage. All these three factors can have an impact on the R0. But in case (1) and (2), masks would also be the ultimate solution. Even if Europe’s ethnicities and strains cause more inflammation and proliferation in the lungs or other mucosa, masks can prevent spreading it into the air and people’s hands.

If the virus doesn’t spread from the mouth to the air, others don’t need to worry. But this luxury is not given in Europe or the US. So, I’m wondering how common and how important aerosols are as a way of infection. In particular, I have this idea that aerosols can get into your eyes even if you wear a mask. What’s your take on this?

  • Thu, Mar 26, 2020 - 05:32am

    #2
    AssessX

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    How Is It Spreading

To add to your question, it seems to me that 15 days to flatten the curve is a very short period of time, particularly with limited adherence to the guidelines. I’d be interested to hear others opinions on the relationship between guidelines and the realistic time needed to actually affect the R0 of this bug.

  • Thu, Mar 26, 2020 - 02:53pm

    #3
    ntd14

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    Reply To: How Is It Spreading

Without doing the math properly,  if it is working, I would expect to see a decrease in new cases between 14 and 21 days, here is why.

If we assume:

An average of 7 days between infection and maximal infectivity (symptomatic)

One person from every household which will ultimately be infected is infected on day 0.

That households are isolated, i.e. transfer within households only, no cross contamination between households.

X number of people get infected at day 0, and each of their households contains y people, which all get infected, and have a 7 day lag.

The peak of the first round of infections will occur at day 7, x cases, when they pass the infection on, 7 days later (day 14) there are x*y cases, i.e. still in exponential growth at day 14, but this should be the peak. Of course there is a delay between becoming symptomatic and getting test results, hence the upper end of 21 days.

In fact we in a week or so we should be able to get a good estimate of the proportional R0 value in Italy after the containment was imposed. With a bunch of assumptions of course. We could probably do it now for SK.

 

Also, there is noise in the data but since the 21st or so it looks like Italy has broken exponential growth, assuming there reporting has not changed.

https://corona.help/country/italy

  • Thu, Mar 26, 2020 - 10:50pm

    #4
    Rachele1

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    How Is It Spreading

I’ve been wanting to point this out for a while now. I have noticed this in China and then South Korea, after they start getting their cases of the HB Virus, they employ heavy disinfecting outside. More importantly in addition to disinfecting hand rails and bus inside buses, they heavily disinfect there streets.

I have searched quit a bit and have found no evidence of any other country implementing this. It does however make sense that if contaminated individuals are coughing, and drops droplets from there saliva are getting on the floors. Someone can then walk over the droplet and carry it somewhere else.

I don’t know, just something I have noticed and it has been bugging me.

  • Fri, Mar 27, 2020 - 06:18am

    #5
    matfax

    matfax

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    People and societies don’t seem to learn

Has anyone read the book or seen the movie “Death in Venice”? Even during the Cholera epidemic back in 1911, they tried to disinfect the streets.

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