Coronavirus - worldwide spread and control

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Just 273 people who arrived in UK in run-up to lockdown were quarantined

Exclusive: Home Office figures cover period when 18.1m people entered country
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Doughty said: “The admission that just four flights from two locations, barely a few hundred individuals – out of literally millions of arrivals – were formally quarantined while the pandemic was already raging in a series of locations beggars belief.

“On what scientific basis were a handful of flights from Wuhan and one from a Tokyo singled out for extreme attention? But not a single flight from Northern Italy, Spain or the US?

“The fact that many of these people then likely arrived and travelled onwards across the UK with little or no adherence to social distancing, and with no checks or protections at the border – barely a whiff of hand sanitiser – is deeply disturbing. Let alone the arrival of 3,000 fans from Madrid as the pandemic picked up speed.

“Yet arrivals continue to this day – with no formal quarantine requirements. It is simply staggering. Who made these decisions? And on what basis?”
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https://www.theguardian.com/world/2...iving-in-uk-in-run-up-to-lockdown-quarantined
 
Covid-19: Confidentiality agreements allow antibody test manufacturers to withhold evaluation results
https://www.bmj.com/content/369/bmj.m1816

Commercial agreements between the UK government and manufacturers of covid-19 antibody tests are allowing the latter to control whether evaluation results of their products are made publicly available.

This matter came to light when a pre-print paper1 assessing nine different antibody tests for covid-19 was published with the names of the tests anonymised. The paper reported that none of the devices were adequate, with sensitivity ranging from 55 to 70% and specificity from 95 to 100%. This was against the Medicines and Healthcare Products Regulatory Agency’s 98% specificity target, which is high because of the risk false positive results could pose if these tests were used to ease lockdown.
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JaneL said:
All the members of (the actual) SAGE group have now been published, except for two members who did not give permission for their names to be released.

You can read the full list of names here:
https://news.sky.com/story/coronavi...ed-after-criticism-over-transparency-11982941

Simon Wessely isn’t on the list.
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He'll be one of the two who didn't give permission. Though I expect he still has direct alarm to the cops still. Possibly the other one is his wife. Just wild guesses! ;)
 
JaneL said:
I think you might be getting specificity and sensitivity mixed up (it’s a bit confusing so easily done!). 99.5% specificity means that 99.5% of healthy people are correctly identified and 0.5% are false positives. Specificity doesn’t tell you anything about how many true positives there are - for that you need to look at the sensitivity.

The reports you have seen on the tests being 70% accurate will be referring to the sensitivity, which you’re right in thinking means that 70% of people with SARS-CoV-2 are correctly identified (and 30% are false negatives). @Snow Leopard mentioned earlier in this thread that the sensitivity for RT-PCR tests are 80%, but also pointed out that reliability is worse if testing is carried out in a random community sample (as opposed to testing a highly selected population showing key symptoms).

https://en.m.wikipedia.org/wiki/Sensitivity_and_specificity

ETA: the reason for false positives is because sometimes SARS-CoV-2 might be mistaken for other pathogens such as the common cold coronaviruses
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I'd forgotten the whole thing about "cross reactivity"; the test isn't specific to a single virus, other similar virus's can give you a positive result. I'm a bit worried since my limited grasp of PCR assumed that the test was highly specific (but if you picked a common gene sequence then not so).

I'd need to sit in a darkened room for a while to think the numbers through!

Thanks to both of you @Snow Leopard @JaneL
 
JaneL said:
Thank you @Snow Leopard for your comments. I wonder whether you find the evidence for asymptomatic transmission presented in the following study anymore compelling? (note it’s a preprint not peer reviewed)

The extract below is from the results section of the paper:

Suppression of COVID-19 outbreak in the municipality of Vo, Italy



https://www.medrxiv.org/content/10.1101/2020.04.17.20053157v1.full.pdf
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Hi, I apologise for not replying sooner, I missed this post earlier. This study does provide suggestive quality evidence that asymptomatic transmission is possible and suggests the importance of larger scale studies to confirm.

There was a range of sampling times for the first survey:
The first survey occurred between 21st and 29th February 2020 and the second survey occurred on 7th March 2020.
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8 new cases (out of 2,343 tests) doesn't give us much to go on statistically and basically assumes the test has 100% specificity and sensitivity.
The testing rates of 85.9% and 71.5% of the population were fairly high, but unfortunately this means the contact tracing is inherently incomplete and there could be additional sources, for example the parent/3 siblings could have been infected via another route. Note that "With symptoms" was "Defined as the presence of fever and/or cough." hence it is possible participants could have had cough or other symptoms but chose not to report them and aren't really "asymptomatic". The study also didn't explain how it dealt with participants who reported symptoms such as cough (but not fever), but tested negative, which could have been false negatives. Also note that participants may be somewhat tight lipped about any individuals who may have violated the lockdown, if they want to protect them from getting into trouble (social desirability bias).

3 cases were apparently contracted from "asymptomatic" individuals, 2 of which did not report any symptoms (note that 3/2343 = 0.1%)
1 "symptomatic" and 1 "asymptomatic" case had no known contacts.
1 "symptomatic" case had a known "symptomatic" contact
2 "asymptomatic" cases had contacts with "symptomatic" cases.

8 cases reported being asymptomatic across at both sampling times. Aside from never having symptoms, I guess they could have been lucky with a sub-15 day period of symptoms, or they chose not to report symptoms, but it's also possible they were false positives. (8/2343 = 0.3%)

From Table 3, only one participant with symptoms had seemingly only been in contact with 'asymptomatic' individuals - but had 4 known contacts from outside the house (perhaps there were more?). Then there is the possibility of these individuals being exposed to 'mild' false negative cases who did not have a fever.

All in all, the results are compelling, but limitations of sample size, completeness of contact tracing, symptom reporting biases, and unknown sensitivity/specificity of the overall testing procedures (there are risks of contamination etc.) mean that the results are not conclusive.
 
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FMMM1 said:
I'd forgotten the whole thing about "cross reactivity"; the test isn't specific to a single virus, other similar virus's can give you a positive result. I'm a bit worried since my limited grasp of PCR assumed that the test was highly specific (but if you picked a common gene sequence then not so).
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The primers are supposed to be quite specific to the virus, but the specificity of a PCR test is not just based on the primers/probes, but everything else that can accidentally go wrong.

https://pubs.rsna.org/doi/10.1148/radiol.2020201343
 
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https://amp.svt.se/nyheter/inrikes/virologer-anvand-munskydd-i-offentliga-miljoer
"Virus researchers: Use oral protection in public environments

The public health authority should encourage the use of mouthguards in public environments and in the elderly to reduce the spread of the corona virus. It writes six virus researchers in a debate article in Dagens Nyheter.

Several European countries have introduced a requirement for citizens to use oral protection, most recently Belgium and Spain, which introduced oral protection requirements in public transport this week. In France, shop owners are given the right to stop customers who do not have face protection.

In Sweden, the discussion has primarily focused on what protective equipment the staff should be entitled to in the elderly, while oral protection among the public has not been seriously discussed. As late as this weekend, state epidemiologist Anders Tegnell told SVT News that there are no studies showing that oral protection protects the wearer from being infected by others, and that those who are sick should stay at home instead of wearing oral protection and go out. .

Drops in the exhaled air
The six researchers, including professors Åke Lundkvist and Fredrik Elgh, now want to raise the issue on the agenda. They refer to two conditions, on the one hand that many are infected without knowing it, and on the other that there are signs that the virus can spread with very small droplets, aerosols, which are found in the exhaled air.

The World Health Organization (WHO) no longer excludes that pathway, although drip and contact infections are still listed as the main pathways of infection, the researchers write in the debate article.

In particular, the virologists point out that the virus is spread on elderly homes and that both residents and staff have been shown to carry the virus without knowing it when tested.

"Unintelligible to discourage"
“In this situation, to discourage the general use of protective equipment in the elderly care system is incomprehensible, especially as the virus in the exhaled air goes down significantly if oral protection is used. In such a contagious, such a serious and, among the elderly, often fatal illness such as covid-19, the precautionary principle must prevail, ”the article states.

Several of the researchers have previously demanded more extensive Swedish measures to counteract the spread of infection. Five of them were among the signatories of the well-publicized call against the Public Health Agency's strategy in mid-April.
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DN Debatt. ”Använd munskydd i publika miljöer och i äldrevården
https://www.dn.se/debatt/anvand-munskydd-i-publika-miljoer-och-i-aldrevarden/


DN Debate. "Use mouth protection in public environments and in elderly care"
Six virology researchers: viruses can be transmitted without the infected person feeling ill and research shows that the infection can spread through the exhalation.

These two features of covid-19 are behind countries introducing oral protection requirements. We are now calling on the Public Health Authority to recommend that oral protection be used in public environments and in elderly care.
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https://translate.googleusercontent...arden/&usg=ALkJrhgsr2z6KxCpjG2tF94w5vqe0UsNlQ

It's baffling to me that personnel in elderly care are discouraged from using protective equipment, as the Swedish Public Health Authorities has admitted to having failed in protecting the elderly and vulnerable. :(
"Better safe than sorry" surely should apply in a situation like this.

“In this situation, to discourage the general use of protective equipment in the elderly care system is incomprehensible, especially as the virus in the exhaled air goes down significantly if oral protection is used.
In such a contagious, such a serious and, among the elderly, often fatal illness such as covid-19, the precautionary principle must prevail, ”the article states."
 
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https://amp.theguardian.com/world/2...-suffered-less-from-coronavirus-than-the-west

Why has eastern Europe suffered less from coronavirus than the west?
Most important reason for discrepancy appears to be implementation of early lockdown


The coronavirus map of Europe makes one thing clear: the richer nations of western Europe have suffered more from the virus than countries in the eastern half of the EU, almost without exceptions.

Comparing figures from different countries can be fraught with difficulty, and many factors can potentially skew the numbers. But the comparison between western Europe on the one hand, and central and eastern Europe on the other, shows a difference in coronavirus rates that is too stark to ignore.

Even the worst-hit central and eastern European countries have infection and death rates per million inhabitants much lower than western European nations, and in some the statistics are truly remarkable: Slovakia has recorded just 1,413 confirmed cases and 25 deaths. Neighbouring Austria, widely regarded as having tackled the challenge of the virus successfully, nevertheless has more than 10 times the number of infections and 20 times the deaths as Slovakia, with a population less than twice the size
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Looks like Donald is going to disband the virus task force. Time to move on and open the economy folks.
 
Snow Leopard said:
Hi, I apologise for not replying sooner, I missed this post earlier. This study does provide suggestive quality evidence that asymptomatic transmission is possible and suggests the importance of larger scale studies to confirm.

There was a range of sampling times for the first survey:


8 new cases (out of 2,343 tests) doesn't give us much to go on statistically and basically assumes the test has 100% specificity and sensitivity.
The testing rates of 85.9% and 71.5% of the population were fairly high, but unfortunately this means the contact tracing is inherently incomplete and there could be additional sources, for example the parent/3 siblings could have been infected via another route. Note that "With symptoms" was "Defined as the presence of fever and/or cough." hence it is possible participants could have had cough or other symptoms but chose not to report them and aren't really "asymptomatic". The study also didn't explain how it dealt with participants who reported symptoms such as cough (but not fever), but tested negative, which could have been false negatives. Also note that participants may be somewhat tight lipped about any individuals who may have violated the lockdown, if they want to protect them from getting into trouble (social desirability bias).

3 cases were apparently contracted from "asymptomatic" individuals, 2 of which did not report any symptoms (note that 3/2343 = 0.1%)
1 "symptomatic" and 1 "asymptomatic" case had no known contacts.
1 "symptomatic" case had a known "symptomatic" contact
2 "asymptomatic" cases had contacts with "symptomatic" cases.

8 cases reported being asymptomatic across at both sampling times. Aside from never having symptoms, I guess they could have been lucky with a sub-15 day period of symptoms, or they chose not to report symptoms, but it's also possible they were false positives. (8/2343 = 0.3%)

From Table 3, only one participant with symptoms had seemingly only been in contact with 'asymptomatic' individuals - but had 4 known contacts from outside the house (perhaps there were more?). Then there is the possibility of these individuals being exposed to 'mild' false negative cases who did not have a fever.

All in all, the results are compelling, but limitations of sample size, completeness of contact tracing, symptom reporting biases, and unknown sensitivity/specificity of the overall testing procedures (there are risks of contamination etc.) mean that the results are not conclusive.
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Thanks so much @Snow Leopard for your analysis of this paper, much appreciated.

I posted the following report which supports the public wearing of face masks in the thread about face masks:
https://rs-delve.github.io/reports/2020/05/04/face-masks-for-the-general-public.html.
The only reason I mention it here is because it rather helpfully collates all the evidence for asymptomatic/pre-symptomatic transmission of SARS-CoV-2. I’m not sure if there is anything in there that you haven’t already seen? (Unfortunately I don’t have the energy myself to look through all the studies and don’t worry if you don’t either!)

I think you’re right though that the two studies that I presented as evidence for asymptomatic transmission, whilst compelling, do not provide conclusive results. So I’m glad you picked me up on that.
 
On May 5, (yesterday), the U.K. had 4,406 new cases. The number of new cases is not going down significantly. (infact according to worldometers, the 7 day moving average was lower on April 28th).

Yet lockdown restrictions expected to be eased. https://www.theguardian.com/politic...rds-as-pm-expected-to-allow-more-time-outside

My partner who had to go out today, reports streets are already getting busier, with more people out and about. I also have been seeing more cars out on the roads outside my flats, for the past 1-2 weeks. I am very worried about a bigger resurgence.
 
lunarainbows said:
On May 5, (yesterday), the U.K. had 4,406 new cases. The number of new cases is not going down significantly. (infact according to worldometers, the 7 day moving average was lower on April 28th)
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The trend for new cases in UK is flat, definitely not going down significantly I would say.

All but 7 US states are also relaxing restrictions, and most of them have increasing cases and deaths.

Cuomo got it right again, new york is now helping the US look good because their numbers are dropping, take new york out of US data and the numbers are getting worse.

Some southern European countries are also expressing desire to open up their tourist economy.

I dread to imagine what the next few months has in store.
 
I think all the focus in a vaccine bring viable in a super short time period is also lulling people into a false sense of security.

I got a very funny look from relatives during Skype session when I simply stated that we don't know enough about the virus to know if a vaccine will work- other coronaviruses have no vaccines and it may be that treatments are developed ( like HIV) instead.

There is a muddling of preventative and curative.

There is an expectation that a vaccine will solve everything.
 
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