Am 28.03.2022 um 19:18 schrieb Charles Ellson:
> On Mon, 28 Mar 2022 14:18:20 +0100, Recliner
> <recliner.usenet@gmail.com> wrote:
>
>> On Mon, 28 Mar 2022 03:08:15 +0100, Charles Ellson <charlesellson@btinternet.com> wrote:
>>
>>> On Sun, 27 Mar 2022 23:23:32 -0000 (UTC), Recliner
>>> <recliner.usenet@gmail.com> wrote:
>>>
>>>> Charles Ellson <charlesellson@btinternet.com> wrote:
>>>>> On Sun, 27 Mar 2022 22:15:19 -0000 (UTC), Recliner
>>>>> <recliner.usenet@gmail.com> wrote:
>>>>>
>>>>>> Charles Ellson <charlesellson@btinternet.com> wrote:
>>>>>>> On Sun, 27 Mar 2022 21:54:54 -0000 (UTC), Recliner
>>>>>>> <recliner.usenet@gmail.com> wrote:
>>>>>>>
>>>>>>>> Charles Ellson <charlesellson@btinternet.com> wrote:
>>>>>>>>> On Sun, 27 Mar 2022 20:46:35 -0000 (UTC), Recliner
>>>>>>>>> <recliner.usenet@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>> Charles Ellson <charlesellson@btinternet.com> wrote:
>>>>>>>>>>> On Sun, 27 Mar 2022 15:53:01 +0100, Recliner
>>>>>>>>>>> <recliner.usenet@gmail.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> On Sun, 27 Mar 2022 15:15:43 +0100, Roland Perry <roland@perry.co.uk> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> In message <t1o8bo$p0d$1@dont-email.me>, at 23:41:44 on Sat, 26 Mar
>>>>>>>>>>>>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>>>>>>>>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>>>>>>>>>> In message <atoe0djbfzse$.dlg@example1357.net>, at 19:37:01 on Thu, 24
>>>>>>>>>>>>>>> Mar 2022, mechanic <mechanic@example.net> remarked:
>>>>>>>>>>>>>>>> On Thu, 24 Mar 2022 11:06:55 +0000, Roland Perry wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I first saw them at scale in a pub which had just reopened with
>>>>>>>>>>>>>>>>> stringent Covid precautions. Tables separated, pre-booked only, one-way
>>>>>>>>>>>>>>>>> system, one person in toilets at a time, table service only etc. It was
>>>>>>>>>>>>>>>>> not at all clear what protection they gave either the waitresses or
>>>>>>>>>>>>>>>>> customers.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> That was when we were fed the 'droplets' theory, science is now
>>>>>>>>>>>>>>>> reluctantly moving to the aerosol idea where earlier instructions to
>>>>>>>>>>>>>>>> clean surfaces and wash hands have given way to more emphasis on
>>>>>>>>>>>>>>>> ventilation and effective masks.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I suppose I always did think it was mainly transmitted by the smaller
>>>>>>>>>>>>>>> droplets know trendily known as aerosols, rather than spit and sneeze.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Still wouldn't want a Covid person to spit in my face though.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Breathing in your direction might be worse.
>>>>>>>>>>>>>
>>>>>>>>>>>>> 2metres, 30 seconds, and both masked, shouldn't be an issue.
>>>>>>>>>>>>
>>>>>>>>>>>> No, probably not, but nor would spitting in those circumstances.
>>>>>>>>>>>>
>>>>>>>>>>> Saliva is generally a far better carrier of infection if it lands on
>>>>>>>>>>> targer.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Are you sure that's true of Covid? It's an airborne virus.
>>>>>>>>>>
>>>>>>>>> It isn't just airborne. The virus is present in saliva, mucous and
>>>>>>>>> other bodily secretions. The difference with saliva (in original form)
>>>>>>>>> is the practical need for more direct transmission from infection
>>>>>>>>> source to entry route (e.g. snogging, spitting on target etc.) than is
>>>>>>>>> needed with aerosols which generally require a relatively longer
>>>>>>>>> presence to enable infection.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Would virus particles present in saliva get into a potential victim's
>>>>>>>> airway?
>>>>>>>>
>>>>>>> Your airway starts at your nose and mouth. Coughing and sneezing can
>>>>>>> cause a heavier and more concentrated stream of saliva than you get
>>>>>>> with an aerosol.
>>>>>>>
>>>>>>> "The virus can spread from an infected person?s mouth or nose in small
>>>>>>> liquid particles when they cough, sneeze, speak, sing or breathe.
>>>>>>> Another person can then contract the virus when infectious particles
>>>>>>> that pass through the air are inhaled at short range (this is often
>>>>>>> called short-range aerosol or short-range airborne transmission) or if
>>>>>>> infectious particles come into direct contact with the eyes, nose, or
>>>>>>> mouth (droplet transmission)."
>>>>>>> https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub/q-a-detail/coronavirus-disease-covid-19-how-is-it-transmitted
>>>>>>>
>>>>>>
>>>>>> A mask wearer is presumably reasonably well protected against droplets
>>>>>> landing on their mouth or nostrils and then breathing in the particles. Is
>>>>>> there any evidence that the virus can be transmitted via the eyes?
>>>>>>
>>>>> Your eyes drain internally to your nose via the nasolacrimal duct;
>>>>> infection via the eye itself is less common. Eye protection is
>>>>> standard kit for ambulance and first aid personnel dealing with
>>>>> potential COVID patients.
>>>>>
>>>>
>>>> Is that precaution based on actual evidence of risk from Covid, or simple
>>>> (sensible) caution all infections?
>>>>
>>> The eye and associated areas have been regarded as a viable route of
>>> infection for over a century :-
>>> https://jamanetwork.com/journals/jama/article-abstract/220430
>>>
>>>> One thing we do know is that a lot of the often misinformed
>>>> Covid precautions have at least protected against other illnesses in the
>>>> last two years. For example, all that hand sanitisng didn't do much to
>>>> block Covid but probably reduced food poisoning.
>>>>
>>> Without experimenting you have no proof for that. COVID was known to
>>> persist longer on non-absorbent surfaces (e.g. handrails, door handles
>>> etc.) while alcohol is efficient in destroying membranes that hold
>>> viruses together as well as being a long-proven general antiseptic.
>>
>> I'm asking what actual research has been done about how Covid is spread. Or are they just assuming it's similar to other
>> diseases (when we know it's not)?
>>
> There is plenty of research material available but as a novel disease
> it is currently more heavily based on observation and experience.
>>
>>> Hand sanitising doesn't work when people don't practise it and I have
>>> been around long enough to see that there are plenty of people who are
>>> best described as selfish filthy bastards when it comes to considering
>>> community hygeine.
>>
>> Yes, I agree that hand sanitising is good for public health, but just question whether it does much to slow the spread
>> of Covid specifically. Has anyone done any actual research? They certainly hadn't when the advice was first given.
>>
> https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/897598/S0574_NERVTAG-EMG_paper_-_hand_hygiene_010720_Redacted.pdf
>
> Note that it can be inferred that standard door handles on
> manually-opened doors, supermarket trolley/basket handles etc. are an
> infection risk which simultaneous use of sanitisation should be
> effective against.

Wait a second: "hand sanitation is effective in reducing respiratory
diseases". This is *not* research specific to COVID.

My understanding is that in early 2020, hand hygiene was one of the
"obvious things to do that might reduce transmission" but that by
mid-2020 still there was no evigence of hand hygiene having an impact on
transmission of COVID.

Out of the three known pathways of transmitting respiratory diseases
(smear infection via hand - eye or hand - mouth, droplet infection and
aerosol infection) it is clear that for COVID, the dominant way of
transmission is aerosol infection; it is not measurable whether smear
infection is relevant for 10% of the infections, for 0.1% of infections
or not at all.

Rolf