Post by b***@nowhere.co.ukOn Mon, 18 May 2020 22:48:56 -0000 (UTC)
Post by ReclinerMasks worn by the public are NOT meant to protect the wearer. They're not
Tell that to all the paranoids wearing them**. 9/10 probably don't have a clue
and 99/100 probably don't realise the virus can easily get into you through
the tear ducks in your eyes just like a common cold so unless they wear a full
face mask they're wasting their time.
** Usually the same morons who cross the street when they see someone coming
to maintain the fatuous 2m distance.
Yes, I think you're right, most members of the public wearing masks
probably still think they're protecting themselves, rather than others. In
shops, I've only noticed staff wearing protective face shields in Waitrose,
and not all staff do.
The 2m thing is like a religious prohibition: vaguely based on a sensible
idea, but implemented thoughtlessly and inflexibly. In reality, people
facing each other and conversing indoors (eg, in a meeting or on a Tube
train) probably need nearer to 3m separation to get much protection, while
people queuing outdoors (face to back) and not chatting loudly need very
little separation for protection — 1m is probably enough.
In London, the chances of a susceptible person meeting an infectious one is
now very small, and the infection won't be passed if they just walk past
each other, or queue behind one another. It appears that most infections
were passed on at 'superspreader events', not casual outdoor encounters:
<https://www.telegraph.co.uk/global-health/science-and-disease/superspreader-events-may-responsible-80-percent-coronavirus/>
A small number of so-called “superspreading” events appear to be
responsible for the great majority of coronavirus cases, raising the
prospect of the virus being controlled if those events can be reliably
pinned down.
Many infectious diseases follow an “20/80” rule, whereby the majority of
cases are caused by a small number of infectious individuals. These include
pathogens such as HIV, measles and Ebola, as well as the coronaviruses Mers
and Sars.
As the journal Nature noted recently, “population estimates of R0 can
obscure considerable individual variation in infectiousness”.
This is now thought to be the case with Covid-19.
An analysis by researchers at the London School of Hygiene and Tropical
Medicine and the Alan Turing Institute strongly suggests there is a “high
degree of individual-level variation” in the transmission of Covid-19.
By applying a mathematical model to reported outbreaks of the disease
outside China, they estimated that 80 per cent of all secondary
transmissions were caused by a small fraction of infected individuals -
around 10 percent.
“Our finding of a highly-overdispersed offspring distribution highlights a
potential benefit to focusing intervention efforts on superspreading”, the
study concluded.
“As most infected individuals do not contribute to the expansion of an
epidemic, the effective reproduction number could be drastically reduced by
preventing relatively rare superspreading events”.
The race is now on to pinpoint and characterise these “superspreader”
events. If we know where the trouble lies we can let the rest of society
open up again.
Tempting though it may be, most experts say we should not look for
individuals. Superspreading events are determined by a complex mix of
behavioural and environmental factors.
Even sexually transmitted viruses like HIV tend to be “superspread” more by
things like needle sharing and prostitution than individuals. Funerals were
a major problem in the 2014-16 Ebola outbreak in West Africa.
With Sars-Cov-2, it seems likely any infected individual could become a
superspreader. Who we are is likely to be less important than where we go
and what we do when we are there.
Already, many superspreading venues are known. Hospitals, nursing homes,
large dormitories, food processing plans and food markets have all been
associated with major outbreaks of Covid-19.
Last week it was reported that four out of five traders (79 per cent) at
Lima’s wholesale fruit market in Peru have tested positive for coronavirus,
for example. In other large markets across the city at least half were
found to be carrying the virus.
Indoor gyms and exercise studios also appear to lend themselves to
superspreading events. A new South Korean study found that 112 people were
infected over 24 days after attending “dance classes set to Latin rhythms”
at 12 indoor sports facilities.
“Intense physical exercise in densely populated sports facilities could
increase risk for infection”, said the authors. “Vigorous exercise in
confined spaces should be minimised during outbreaks”.
Just over half of the cases were the result of transmission from
instructors to those attending the dance classes and the overall attack
rate was a high 26.3 percent.
Characteristics that may have led to the outbreak included “large class
sizes, small spaces, and the intensity of the workouts”, said the study.
“The moist, warm atmosphere in a sports facility coupled with turbulent air
flow generated by intense physical exercise can cause more dense
transmission of isolated droplets”, it noted.
The researchers did not find any cases where classes were limited to five
people or less. Also, pilates and yoga appeared to pose a lesser risk than
dance.
“We hypothesise that the lower intensity of pilates and yoga did not cause
the same transmission effects as those of the more intense fitness dance
classes,” said the authors.
But you don’t have to be dancing to be exhaling vigorously while in the
close contact of others.
In Washington State on the west coast of America, a church choir went ahead
with its weekly rehearsal in early March even as Covid-19 was sweeping
through Seattle, an hour to the south. Dozens of its members went on to
catch the virus and two died.
The Washington singers were not the only choristers to be hit. Fifty
members of the Berlin Cathedral Choir contracted the virus after a March
rehearsal, and in England many members of the Voices of Yorkshire choir
came down with a Covid-like disease earlier this year.
A choir in Amsterdam also fell victim to the virus, with 102 of its 130
members becoming infected after a performance. One died, as did three of
the chorister's partners.
Research suggests it is not the singing alone that causes the spread of the
virus but the close contact that goes with it.
“These outbreaks among choir members all occurred during the early days of
the Covid-19 pandemic, before lockdowns were imposed and before our minds
were concentrated on the importance of social distancing”, Professor
Christian Kähler of the Military University, Munich, told the Guardian
newspaper.
“Choir members probably greeted each other with hugs, and shared drinks
during breaks and talked closely with each other. That social behaviour was
the real cause of these outbreaks, I believe.”
One of the biggest superspreading events in Europe came in the February
half term holidays when thousands of people gathered in alpine ski resorts.
Hundreds of infections in Germany, Iceland, Norway, Denmark and Britain
have been traced back to the resort of Ischgl in the Tyrolean Alps. Many
had visited the Kitzloch, a bar known for its après-ski parties.
The bar is tightly packed and famous for "beer pong" – a drinking game in
which revellers take turns to spit the same ping-pong ball into a beer
glass.
Earlier this year The Telegraph obtained a video from inside the Kitzloch.
It may yet come to define the perfect superspreader event, with attendees
all singing along to AC/DC’s Highway to Hell:
<video>
In London, cases of coronavirus have dropped dramatically since the
lockdown. The superspreading events that were once spreading the virus so
widely have now stopped.
The challenge now facing investigators is to work out what they were in the
first place.