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COVID-19 / Re: Efficacy - Comparing Like with Like

« on: 10/01/2021 14:22:47 »

If one trial is testing the subject every week - then it will identify the asymptomatic infection; if another trial is only testing when symptoms develop then it will miss the asymptomatic infection and so give a different measure of efficacy?

Both measured efficacy in the same way, the primary outcome - efficacy against symptomatic cases of covid-19 - which showed that the Oxford vaccine was 62.1% effective in participants who received two standard doses.
The Oxford trial also monitored for asymptomatic infections as a secondary outcome, which the Pfizer trial does not appear to have done.
 

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COVID-19 / Re: Is it possible to be infected by Covid-19 while exercising alone outdoors?

« on: 21/03/2020 07:29:26 »

I heard of some measurements by the US NIS that measured the half-life of infectious viral particles on various surfaces.

They found that half of the virus was still infectious after an hour when created in the form of an aerosol (virus particles floating in the air).

So when you are out walking or cycling, you are potentially breathing in virus particles left by someone who passed that way an hour before.
- If there is a breeze, you may be breathing in virus particles expelled by a sneeze from an infected person a mile away.

Of course, the outdoors has a higher level of UV light from the Sun than you would find in an indoor lab.
- UV would tend to inactivate virus particles faster
- And the outdoors has a lot more volume in which to spread out the virus particles, so you are less likely to breathe in an active virus than if you spent an hour in a small room with an infected person.
- But this only works if there are no infected people outdoors; later in the pandemic, when there are many infected people, if they are all outdoors, you are better off inside by yourself.

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COVID-19 / Re: Are face masks effective against Covid-19 transmission?

« on: 14/03/2020 15:24:30 »

This may help
https://www.hse.gov.uk/research/rrpdf/rr619.pdf