Domestic Travel Covid Testing
#22
#24
"However, the method was also used in a group of schoolchildren and teachers in Beijing last week, according to multiple reports. Throat and nose swabs were also used in the group. "
Hopefully they did the anal swab last.
Hopefully they did the anal swab last.
#25
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Joined APC: Dec 2019
Posts: 472
#26
So you have people that are not close to infectious testing positive, and then have to try to figure out how they got COVID-19? must have been the mysterious asymptomatic transmission.
#27
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Joined APC: Mar 2011
Position: Bizjet Captain
Posts: 251
My personal belief has always been that there might not be any such thing as asymptomatic spread - just running too many cycles on the flawed PCR tests that detect such minute traces of COVID DNA (still a "positive"). If you run enough cycles on a sample, you could could be finding a very old infection, or an infection of something like COVID but not, or something else entirely. Google it; this is a known, medically understood flaw in our testing programs.
So you have people that are not close to infectious testing positive, and then have to try to figure out how they got COVID-19? must have been the mysterious asymptomatic transmission.
So you have people that are not close to infectious testing positive, and then have to try to figure out how they got COVID-19? must have been the mysterious asymptomatic transmission.
https://www.bmj.com/content/371/bmj.m4851
In short, asymptomatic spread is much less of a thing than initially estimated. Based on whar they know now they thini asymptomatic spread accounts for less than 20% of the cases.
However, many people who were initially thought to be asymptomatic went on to develop symptoms later, so were really pre-symptomatic. Pre-symptomatic people play a significant role in transmission as they carry enough life virus to be contagious without having symptoms yet.
The article also talks about the limitations of PCR testing as the sole criterion for determining infection.
#28
Here is an excellent, recent article on asymptomatic spread from the British Medical Journal
https://www.bmj.com/content/371/bmj.m4851
In short, asymptomatic spread is much less of a thing than initially estimated. Based on whar they know now they thini asymptomatic spread accounts for less than 20% of the cases.
However, many people who were initially thought to be asymptomatic went on to develop symptoms later, so were really pre-symptomatic. Pre-symptomatic people play a significant role in transmission as they carry enough life virus to be contagious without having symptoms yet.
The article also talks about the limitations of PCR testing as the sole criterion for determining infection.
https://www.bmj.com/content/371/bmj.m4851
In short, asymptomatic spread is much less of a thing than initially estimated. Based on whar they know now they thini asymptomatic spread accounts for less than 20% of the cases.
However, many people who were initially thought to be asymptomatic went on to develop symptoms later, so were really pre-symptomatic. Pre-symptomatic people play a significant role in transmission as they carry enough life virus to be contagious without having symptoms yet.
The article also talks about the limitations of PCR testing as the sole criterion for determining infection.
From the article - "It’s also unclear to what extent people with no symptoms transmit SARS-CoV-2. The only test for live virus is viral culture. PCR and lateral flow tests do not distinguish live virus. No test of infection or infectiousness is currently available for routine use. As things stand, a person who tests positive with any kind of test may or may not have an active infection with live virus, and may or may not be infectious"
Also "The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms. A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission. Coughing, which is a prominent symptom of covid-19, may result in far more viral particles being shed than talking and breathing, so people with symptomatic infections are more contagious, irrespective of close contact. On the other hand, asymptomatic and presymptomatic people may have more contacts than symptomatic people (who are isolating), underlining the importance of hand washing and social distancing measures for everyone."
This makes too much logical sense, though. Instead we figure we should triple mask up.
#29
Gets Weekends Off
Joined APC: Mar 2011
Position: Bizjet Captain
Posts: 251
Great article. I wish our policy decisions were based on this kind of scientific review rather than hysteria. I do take exception to the one thing that you bolded though - I don't remember seeing any conclusion in that article that presymptomatic people play any significant role - in fact, I think the point was we don't know and are making assumptions (perhaps invalid) based on testing not for infectiousness but just for genetic presence of virus, past or present.
From the article - "It’s also unclear to what extent people with no symptoms transmit SARS-CoV-2. The only test for live virus is viral culture. PCR and lateral flow tests do not distinguish live virus. No test of infection or infectiousness is currently available for routine use. As things stand, a person who tests positive with any kind of test may or may not have an active infection with live virus, and may or may not be infectious"
Also "The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms. A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission. Coughing, which is a prominent symptom of covid-19, may result in far more viral particles being shed than talking and breathing, so people with symptomatic infections are more contagious, irrespective of close contact. On the other hand, asymptomatic and presymptomatic people may have more contacts than symptomatic people (who are isolating), underlining the importance of hand washing and social distancing measures for everyone."
This makes too much logical sense, though. Instead we figure we should triple mask up.
From the article - "It’s also unclear to what extent people with no symptoms transmit SARS-CoV-2. The only test for live virus is viral culture. PCR and lateral flow tests do not distinguish live virus. No test of infection or infectiousness is currently available for routine use. As things stand, a person who tests positive with any kind of test may or may not have an active infection with live virus, and may or may not be infectious"
Also "The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms. A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission. Coughing, which is a prominent symptom of covid-19, may result in far more viral particles being shed than talking and breathing, so people with symptomatic infections are more contagious, irrespective of close contact. On the other hand, asymptomatic and presymptomatic people may have more contacts than symptomatic people (who are isolating), underlining the importance of hand washing and social distancing measures for everyone."
This makes too much logical sense, though. Instead we figure we should triple mask up.
"Viral culture studies suggest that people with SARS-CoV-2 can become infectious one to two days before the onset of symptoms and continue to be infectious up to seven days thereafter; viable virus is relatively short lived.7Symptomatic and presymptomatic transmission have a greater role in the spread of SARS-CoV-2 than truly asymptomatic transmission"
#30
Which has been known to be the case by anyone educated in public health since Bayesian Probability was first developed in the late 1700s.
http://pages.stat.wisc.edu/~ifischer...se_Testing.pdf
The only real issue is whether our elected politicians are merely abysmally ignorant, intractably stupid, or just snowflakes, although I suppose ‘all of the above’ might also be in play.
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