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Corona / Covid-19 Virus - General Discussion (politics go to the Off Topic / Politics thread)

Evidence that in "normal"circumstances that I outlined in my previous post this degree of protection is actually required.

If you have an airborne virus, or some other toxic substance, you cannot protect yourself getting some exposure using the PPE currently used.

I am relating this to handling industrial chemicals where this stuff is pretty well known and sorted out.

The difference is that a little bit of leakage with some common chemical or a toxic paint is not going to kill you, but a sniff of CV19 clearly might. The high infectiousness must mean that not much of it is required to overwhelm the immune system. And where some substance could kill you (for example labs working with nerve gases) they use pressurised airtight suits.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

If you have an airborne virus, or some other toxic substance, you cannot protect yourself getting some exposure using the PPE currently used.

I am relating this to handling industrial chemicals where this stuff is pretty well known and sorted out.

The difference is that a little bit of leakage with some common chemical or a toxic paint is not going to kill you, but a sniff of CV19 clearly might. The high infectiousness must mean that not much of it is required to overwhelm the immune system. And where some substance could kill you (for example labs working with nerve gases) they use pressurised airtight suits.

But that is obviously not going to happen Peter. And while it can kill you, the chance remains incredibly low.
Last Edited by JasonC at 08 May 21:13
EGTK Oxford

A reasonable article on viral loads and the immune response relating to covid-19

https://www.sciencemediacentre.org/expert-reaction-to-questions-about-covid-19-and-viral-load/

Dr Michael Skinner, Reader in Virology, Imperial College London, said:

“Some comments on virus dose, load and shedding.

“Viruses are not poisons, within the cell they are self-replicating. That means an infection can start with just a small number of articles (the ‘dose’). The actual minimum number varies between different viruses and we don’t yet know what that ‘minimum infectious dose’ is for COVID-19, but we might presume it’s around a hundred virus particles.

“When that dose reaches our respiratory tract, one or two cells will be infected and will be re-programmed to produce many new viruses within 12-24 hours (for COVID-19, we don’t yet know how many or over how long). The new viruses will infect many more nearby cells (which can include cells of our immune defence system too, possibly compromising it) and the whole process goes around again, and again, and again.

“At some time quite early in infection, our ‘innate immune system’ detects there’s a virus infection and mounts an innate immune response. This is not the virus-specific, ‘acquired immune response’ with which people are generally familiar (i.e. antibodies) but rather a broad, non-specific, anti-viral response (characterised by interferon and cytokines, small proteins that have the side effect of causing many of the symptoms: fever, headaches, muscle pain). This response serves two purposes: to slow down the replication and spread of the virus, keeping us alive until the ‘acquired immune response’ kicks in (which, for a virus we haven’t seen, is about 2 to 3 weeks) and to call-up and commission the ‘acquired immune response’ which will stop and finally clear the infection, as well as laying-down immune memory to allow a faster response if we are infected again in the future (this is the basis of the expected immunity in survivors and of vaccination).

“With COVID-19, these two arms of the immune system (innate and acquired) obviously work well for 80% of the population who recover from more or less mild influenza-like illness.

“In older people, or people with immunodeficiencies, the activation of the acquired immune system may be delayed. This means that the virus can carry on replicating and spreading in the body, causing chaos and damage as it does, but there’s another consequence. Another job of the acquired immune system is to stand-down the innate immune system; until that’s done the innate immune response will keep increasing as the virus replicates and spreads. Part of the innate immune response is to cause ‘inflammation’. That is useful in containing the virus early in an infection but can result in widespread damage of uninfected tissue (we call this a ‘bystander effect’) if it becomes too large and uncontrolled, a situation named ‘cytokine storm’ when it was first seen with SARS and avian influenza H5N1. It is difficult to manage clinically, requiring intensive care and treatment and carries with it high risk of death.

“The scenarios described above describe what happens following infection with ‘normal’ doses of virus, both in those who make a recovery, those who require intensive care and those (mainly elderly and/or immunosuppressed) who might succumb. Those with other comorbidities probably succumb due to additional stress of their already compromised essential systems by virus and/or cytokine storm.

“It is unlikely that higher doses that would be acquired by being exposed to multiple infected sources would make much difference to the course of disease or the outcome. It’s hard to see how the dose would vary by more than 10 fold. (Although differences have been seen in lab animal infections with some viruses, those animals are inbred (genetically similar to respond in the same way). It’s unlikely that we’d see the differences as statistically significant in out-bred humans.)

“We must be more concerned about situations where somebody receives a massive dose of the virus (we have no data on how large that might be but bodily fluids from those infected with other viruses can contain a million, and up to a hundred million viruses per ml), particularly through inhalation.

“Unfortunately, we don’t yet know enough about the distribution of the COVID-19 virus throughout the body of the infected patients in normal, and unusual situations.

“Under such circumstances the virus receives a massive jump start, leading to a massive innate immune response, which will struggle to control the virus to allow time for acquired immunity to kick-in while at the same time leading to considerable inflammation and a cytokine storm.

“For most of us, it’s hard to see how we could receive such a high dose; it’s going to be a rare event. In the COVID-19 clinic, the purpose of PPE is to prevent such large exposures leading to high dose infection. Situations we should be concerned about are potential high dose exposure of clinical staff conducting procedures on patients who are not known to be infected. I read about a Chinese description of an early stage COVID-19 infection of the lung, which only came about because lung cancer patients (not known to be infected) had lobectemies. There have been suggestions that such situations contributed to the deaths of medics in Wuhan, who were conducting normal procedures (including some that could generate aerosols of infected fluids) before the spread and risk had been appreciated.

“Obviously, testing of patients for infection should now be a priority for any such procedures. Some of the relevant elective procedures have been postponed or scaled back (for patient and staff safety) but we can’t do the same for non-elective procedures (especially in emergency and maternity departments).”

Perhaps the covidiots were not so silly

Last Edited by Ted at 08 May 21:48
Ted
United Kingdom

It’s very hard for us hoi polloi to know what the risks to healthcare workers are. The Guardian has counted 165 deaths amongst healthcare workers that have been publicised. The government hasn’t shared any meaningful figures.

On one hand 165 deaths is not that many, but they will be concentrated amongst a relatively small cohort of people. For example, if you are working in the miasma of a COVID ward in London, the risks are worth considering, particularly if you are black or Middle Eastern and approaching retirement age. I think these people are genuinely brave.

At present, I personally feel no fear as I walk into work every morning, and I feel embarrassed every Thursday when the clapping begins. For the first time in years I have a manageable workload and I am starting to feel human again.

we might presume it’s around a hundred virus particles.

That’s not a lot, at ~ 100nm diameter each. That’s one miniscule drop of liquid.

has counted 165 deaths amongst healthcare

The NHS employes > 1M people, and across the UK ~500ppm have died, so you would expect ~500 in the NHS.

The 500 would need to be adjusted down for age (NHS workers are not going to be old and frail) and then adjusted up for the increased BAME risk (the NHS has above average BAME population working there).

I wonder if anyone has correlated this 165 with where they actually worked? That would be such an obvious thing to do! Quoting just the total is meaningless.

Administrator
Shoreham EGKA, United Kingdom

For those interested in how the virus propagates, this is essential reading:

https://erinbromage.wixsite.com/covid19/post/the-risks-know-them-avoid-them

LFMD, France

I think many will agree that testing is important but carrying out something like 66 million tests, perhaps more than once would pose a big problem.
Because of that an epidemiologist here is suggesting that we test the sewage water, which although not able to test individuals would be a quick way to narrow down geographical areas which have cases such as towns and cities.

France

kwlf wrote:

the risks are worth considering, particularly if you are black or Middle Eastern and approaching retirement age. I think these people are genuinely brave.

It’s interesting also that if you’re male it appears you’re more at risk too. But this doesn’t seem to get brought up nearly as much.

I’ll share what’s happened in Jersey EGJJ. Our whole lock down has been far less strict than the UK.

Somewhere near the start we had a higher infection rate per capita than the UK, although this might have been due to testing at 3 times the rate.

We have always been allowed to go out for almost any reason for 2 hours, we could swim in the sea, surf. After surfing you could sit a few minutes in the sun and kids could play in the beach. The slight breach was ignored as long as social distancing was observed. As this topped up vitamin D perhaps this was the most important thing. Garden Centres were always open as were small tradesman, window cleaners. Any office could work if it had 2 people in and anybody could work *essential or non essential" if you could maintain social distancing.

Our infections have gone to zero. It makes you wonder how many of of the oppressive UK rules were needed

United Kingdom
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