jmastron

My mind is boggled at some of the irresponsible communication styles -- The WHO (and all scientists) REALLY need to get some remedial communication help.

Her actual tweet isn’t too misleading: “2/2 ... on transmission from asymptomatic individuals are difficult to conduct, but the available evidence from contact tracing reported by Member States suggests that asymptomatically-infected individuals are much less likely to transmit the virus than those who develop symptoms”

But her interview statements: “seems to be rare that an asymptomatic person actually transmits onward” followed by “It’s very rare” are pretty misleading. She should have known that would be taken by those with an agenda (and some without) as if all of the precautions, lockdowns, and “wear a mask even if you don’t feel sick” were useless, and as if “stay home if sick” is all we ever needed, when that really isn’t the case.

1) They’re making a big distinction between “asymptomatic” (never get symptoms) and “pre-symptomatic” (don’t have symptoms YET). Fine for scientific hindsight analysis, but the point all along is that you can spread it when you feel fine (right now) so need to take precautions (right now) even if you “don’t feel sick”.

2) I can’t find where they actually present the percentage data behind the “much less likely” statement, and note that like I said somewhere else they’re saying the *source* is less likely to transmit. The more important number to me is what percentage of *targets* are infected from either an asymptomatic carrier *or* a pre-symptomatic one. That number has to be pretty high, otherwise this thing wouldn’t be spreading since even the hardcore nonbelievers are going to avoid someone actively having COVID symptoms.

3) Tracking “symptoms” in hindsight is difficult, as she mentions in another tweet, because some of the symptoms are close to allergies and other illnesses. I’ve had some mild allergies recently that come and go and are *most likely* just that, but...if I test positive next week does that mean I count as “asymptomatic” or not? I suspect this effect is even higher in nursing homes and other places where it seems they took the most data.

To reiterate: The WHO is NOT saying that people who feel fine don’t transmit COVID-19!

Temedar

The official death count for all of China is 4634 (according to Worldometer), so your math is quite a bit off.

wco81

Bergamo antibody testing shows 57% of a 10,000-person sample shows antibodies. Again caveats about the accuracy of antibody tests and all that.

https://www.dw.com/en/coronavirus-te...ies/a-53739727

fransknorge

If this number is correct I think that does not bode well for the theory that kappa for COVID-19 would be 0.2-0.4, as such a low kappa and a R0 of 2 would mean herd immunity at 20-30%. Am I correct ?

doctoravios

In that case I think the conclusion is that serology is not reliable or that different studies are operating at different thresholds for positivity (depending on the assay). I cannot think of other explanations which, taken together, would explain such a great difference between Wuhan and Bergamo. Yes, sampling bias and differences in lockdown/population exposure might make some difference but surely not a 50% difference?

stan1162

I'm sure this will get moved, but here goes. I was deathly ill early March with suspected Covid. I was about 1/2 hour away from going to the ER. Somehow I knew if I went to the hospital, I wouldn't come home alive. I've had blood clots in my lungs, so I am familiar with unbelievable shortness of breath. Fever, headache, absolute exhaustion, nausea, ALL the symptoms. Mid-late March Son in law lost smell/taste and 12 hour fever. Daughter had shortness of breath, headache, fever, she was way more ill than he.

Of the 3 of us, he is the only one who tested positive for antibodies... Something is amiss. Is the assay threshold set intentionally high so there is a low number of positives being reported for poitical reasons??? High numbers of anything COVID related look bad. I'm not a conspiracy theorist, but I am very suspicious.

GadgetFreak

I think they want high number in most case since they mean the population has more people potentially immune and the higher the number of cases the lower the death rate. My understanding it's just a hard test to get right and they don't want to tell people that they are potentially immune when they aren't.

doctoravios

Most likely serology assays (even those based on robust quantitative methods such as CLIA and ECLIA) are not measuring presence of antibodies in a reproducible way. Or, there genuinely is a lack of a significant antibody response even in serious illness and it mostly comes down to a cell-mediated response. Personally, I think it is unlikely that someone with serious symptoms would have zero binding antibodies (though it is possible that not everyone mounts a neutralising antibody response). As GadgetFreak says, I think at this stage it is more likely to be explained by technical limitations and a lack of understanding of the immune response which may take years to even remotely understand.

Either way, any hope of a reliable method to determine previous infection is out of the window for the time being. Perhaps it will require a combination of antibody testing and cytokine assays (like ELISPOT)?

FlyBitcoin

Nothing political. This is all new and each test out there (of the 80 or so available) looks at different thresholds and different antibodies.
Re-test your serum at a different lab that is using a different reference test.
Roche and Abbott are solid ones. Don't use a rapid test kit (which looks like a home pregnancy test).
Make sure specificity is above 98% and on this list: https://www.centerforhealthsecurity....-COVID-19.html

cesco.g

Is the Roche ECLIA test already on the US/EU market?

doctoravios

It is certainly available in the EU. Just be aware that even the Roche test is having some issues with sensitivity. It was licensed based on a sensitivity of 100% but tested in just 29 patients.

https://diagnostics.roche.com/global...ars-cov-2.html

Public Health England has done further tests and found the sensitivity has been overestimated and they make it around 86%:

https://www.gov.uk/government/public...logical-assays

However, this is with quite a high cut-off point which PHE argue could be reduced slightly.

N.B. Bear in mind that the reference standard was a previous positive RT-PCR test. This is comparing apples and pears (i.e. PCR vs serology) and perhaps a more meaningful comparison would be an antibody neutralisation assay. But they are quite time consuming/resource intensive to do.

MSPeconomist

Does anyone understand the new immunity test that was developed by Mayo Clinic?

It seems to be garbled on local TV news, but supposedly tests whether the person has had COVID-19 and is presumably somewhat immune from getting it again, but the test isn't based on antibodies. I don't know whether it's a blood test.

ADDED: A local reporter describes it as a test "to identify specifically neutralizing antibodies" that can also be used to pick the best therapeutic plasma donors. It's being described as a subset of more specific antibodies that are able to inactivate the COVID-19 virus by itself.

Another local reporter has repeated that the test isn't based on antibodies but rather the "proteins produced."

radonc1

Just to point out that not all delays in the vaccine game are due to the development of an effective agent An interesting story from Reuters.

Exclusive: Bottlenecks? Glass bottle makers prepare for Covid-19 Vaccine

"Drugmakers are warning of a potential shortage of vials to bottle future COVID-19 vaccines, but their rush to secure supplies risks making matters worse, some major medical equipment manufacturers warn...................
Corning this week won $204 million in U.S. government funding to boost output of its vials for COVID-19 vaccines and treatments. That came a day after the U.S. government awarded $143 million to SiO2 Materials Science to boost production of its vials and syringes."

Many don't appreciate just how complex the development of a supply chain is or what goes into producing a treatment (besides the expected research and development ).
This is just a little unknown story of how government and industry are working together to produce the supply and logistics necessary to carry out the treatment (if it occurs) using vaccines.

FlyBitcoin

Behind a paywall for many: https://www.wsj.com/articles/before-...it-11591959600
Looks again at why some people have innate T-cell immunity to SARS-CoV2

Highlights....

fransknorge

FlyBitcoin: have you seen any research on peptide presentation by antigen to T-Cell associated with SARS-COV-2 ? I have in mind something similar to how HLA-B27 give a natural immunity to influenza A, HIV-1, hepatitis C and Epstein Barr .
https://www.annualreviews.org/doi/fu...-032414-112110