Asymptomatic Transmission...

[kellehi]

First of all, I'm aware that this will probably start a pile on, but I was intending to reply to @MarshaBradyo as we were discussing the basis for asymptomatic transmission, and I promised that I'd dig out the RKI paper that in February 2020 first started up the reasoning that Covid-19 was primarily being spread by asymptomatic transmission and the discussions critiquing it... However, the thread presumably reached its page limit and had gone off topic anyway, as long threads are prone to do...

Since we have seen little actual evidence on the basis of claiming asymptomatic transmisson is a substantial driver of the Covid-19 outbreak compared to symptomatic transmission except from appeals to authority - i.e. 'X government scientist said so' without providing reference to sources, I started out wondering, does anyone have any ideas on what basis were experts claiming that Covid-19 asymptomatic spread is a thing and we needed to lock down in March last year? Are there any studies, peer reviewed papers, other sources that I can read up on?

At the time I thought it'd be incredibly hard to prove definitively that someone who is asymptomatic for Covid-19 is spreading the virus, and probably would be extremely unethical to carry out a study whereupon you expose people to known asymptomatic (tested positive but not unwell) patients to see if they developed symptoms later. So I did some research to try to uncover what was the basis for determining asymptomatic transmission at the start of the outbreak.

I tried asking around and I got 'we know better, don't you know this is a thing, the Robert Koch Institute have proved this, and by the way there's people dying of this stuff being infected by their family members who are tested and found to be asymptomatic'

Doing some digging on their paper reveals a link that says "Study claiming new coronavirus can be transmitted by people without symptoms was flawed". and further down the page is an article right from the start of the pandemic when there were little to no other existing sources of asymptomatic transmission to rely on...

www.medpagetoday.com/infectiousdisease/publichealth/84688

Asymptomatic transmission of the novel coronavirus in Germany was called into doubt on Monday when an article appeared to question the research behind it.

Science magazine detailed errors in the New England Journal of Medicine (NEJM) research letter published last Thursday. The letter reported that asymptomatic transmission of novel coronavirus occurred in Bavaria, Germany, when several co-workers of an asymptomatic woman traveling from China contracted the virus.

The letter, and several media reports, said that the woman wasn't sick when she was in Germany and only began to feel ill on the plane ride home. Turns out that wasn't quite true.

Researchers who wrote the NEJM letter did not speak to the woman herself, according to Science. But after she spoke to officials from the Robert Koch Institute, Germany's public health agency, and Bavarian officials, she said that she "felt tired, suffered from muscle pain," and took fever-lowering medication while in Germany.

While Germany's health agency spokespeople would only confirm that the woman had symptoms, the Robert Koch Institute has submitted a letter to NEJM, presumably to correct the record.

China has claimed to have data showing asymptomatic transmission occurring within the country, but U.S. health officials previously said that they did not have enough data to make that claim. That appeared to change after the publication of the NEJM letter.

Indeed, asymptomatic transmission outside China was alluded to when the U.S. declared a public health emergency for novel coronavirus on Friday. And on Saturday, the World Health Organization (WHO) reported "third-generation" transmission of the virus in Germany.

Science said that WHO officials and European partner agencies have been notified with the new information. As of Tuesday, NEJM has not published a letter of correction.

Last Updated February 04, 2020

Two comments from below the article:

Brant S MIttler, MD JD (perhaps the same as medicine.duke.edu/faculty/brant-s-mittler-md)

February 5, 2020

I have been tweeting for some time now for some federal agency or an on-the-ball media outlet to please tell us ALL of the evidence that there is "asymptomatic transmission" of the virus. Being a "nobody," nobody responds. Maybe one of the editors or writers or maybe even the new Editor in Chief of this august online publication could break out of the pack and assemble and publish that evidence? As to the 10 yo boy with pneumonia who was supposedly asymptomatic, my pediatric colleagues doubt that patient was truly asymptomatic. Since we now have a public health emergency, it seems reasonable to look at the quality of the evidence for "asymptomatic transmission." Now I will sit back and wait for all the infectious disease and public health mavens to educate us.

Reza Nassiri (perhaps this Professor... phmtox.msu.edu/people/faculty/nassiri/)

February 9, 2020

The German investigators hastily rushed to submit their report to NEJM without hypothesizing the “biological” basis of asymptotic 2019-nCoV. Most importantly, they failed to consult with epidemiologists and virologists while preparing their investigational report which turned out to be partially inaccurate. Take home message: while there are currently uncertainties of various kinds about Whuhan vial pneumonia, better consult with multidisciplinary science team rather than rushing to submit a report. Prof. Nassiri

I've been thinking this for a while. I think it's been very overstated.

I also think that being 'true' asymptomatic is very rare indeed. I know lots of people that have tested positive and everyone, at some point, loss their taste and/or smell.

It was my sister's only real symptom aside from feeling tired. She tested positive on a LFT 7 days prior to losing her taste.

Youre missing the point.
We are testing symptomatic and asymptomatic to reduce the r value.
Obviously in say care homes/stadiums/planes it's important to try to not have anyone infected.

But with the vax the r will drop anyway as in say each classroom of 30 there are say 60 parents. But already 15 are vaxxed.
So 45
And only say 1 of the other 15.
Once all the parents are vaxxed that will reduce to very few and those may/may not spread it to anyone else.

Anyway i don understand why there are no animal tests of either other covid infected animals or of people infecting animals which asymptomatic.

The reason just not coughing isnt enough is that we aerosolise when singing/shouting and talking too. Aside ftom lots of people sneeze many times a day.

Scientific experimentation can only prove hypotheses in a controlled environment. A sterile environment where the factor under investigation is serially subject to potential causal factors one at a time.

Real life data can only 'prove' a hypothesis to the extent that all other potential causal factors can be controlled.

Given the number of symptomatic cases and lack of tracing data it is impossible to say where infection came from.

In this open and messy environment it is impossible to prove scientifically whether infection was spread by symptomatic, presymptomatic, asymptomatic, vaccinated, unvaccinated etc.

So we have to rely on theory of what the case is expected to be. But then we have to layer political policy that favours some theories and discounts others. Then we have to layer economics that privilege some theories and discount others.

The idea that science occupies a higher realm was discounted long ago eg Thomas Kuhn and the structure of scientific revolutions. He basically argued that scientific paradigms operate until they are overwhelmed by an accumulation of contrary data.

So the revolution could be that asymptomatic spread is not a relevant factor wrt to health but allowed increased social control.

Or that spread continued once the symptomatic were isolated and that all contacts needed to isolate whether or not symptomatic. Or that maybe Imask protocols of treatment would have reduced morbidity and mortality without negatively effecting vaccination. May have even been a boost to vaccination.

Or that vaccination of the symptomatic and asymptomatic is treated differently to the never infected. Or that you have to pretty much eradicate the virus before you vaccinate.

There are studies that clearly state that imperfect immunisation creates vaccine resistance.

This is clearly stated in reports that focus on the fact that the majority of those immunised are not infected. What about those who are immunised and infected?

How did they become infected? You ever hear of this? I and my D.C. have had loads - measles, mumps, rubella, TB, hepatitis, lockjaw plus others I can't remember etc. Maybe that because you or your D.C. never had a vaccine during high circulation of a virus. Maybe because it's never been done before.

It's quite clear that he means asymptomatic and English isn't his first language.

Neither is mine. So?
If he knows anything about transmission, he'd know very well the difference between the two terms. His field is pharmacology. Perhaps not THE best expert to evaluate transmission.

The current guidelines state that transmission is stronger from 2 days before symptom onset.

My own experience of people I know supports this.

It's not really disputed.

Pre-or no symptoms at all, temperature measuring or symptom reporting are not good control measures at all.
We still need to assume we could be infectious and other people could to, despite seeming fine.

The question of how important is transmission by people who never show symptoms is more for modellers.

In this open and messy environment it is impossible to prove scientifically whether infection was spread by symptomatic, presymptomatic, asymptomatic, vaccinated, unvaccinated etc.

Shocking news, the scientific method proves nothing, only disproves.

But quite a lot of scientific research, particularly where humans are concerned, is done under real-life conditions. And lab conditions can be quite artificial. None is ideal.
Epidemiologists do have many tools to control for messy real life. Fascinating field. Worth studying properly.

@Lweji

It's quite clear that he means asymptomatic and English isn't his first language.

Neither is mine. So?
If he knows anything about transmission, he'd know very well the difference between the two terms. His field is pharmacology. Perhaps not THE best expert to evaluate transmission.

Yes, lets disregard his whole career just because he used a wrong word that is similar to the word of appropriate meaning.

A word that if you stopped 1000 English people on the street and asked them what it meant, I'd be surprised if even 1% would be able to define it correctly...

Erm... his whole career is not on infectious disease transmission...
And the wrong term is the tell-tale sign of a non-expert.

Do you understand what a pharmacologist does?

I see all sorts of so-called experts dishing out comments about covid. I'd rather read proper articles, preferably articles written not more than a few months ago, when a lot more is known about the disease and its transmission, than from more than a year ago, when it was all very unclear.

Some people just like to get their opinions out, very loudly. It doesn't make them right.

And other people like to search for confirmatory opinions, regardless of who wrote them, and when.

Epidemiologists are great but they are not the be end and end all are they - they're not expected to be doctors or nurses or natural or social scientists or psychologists or immunologists or have powers of prediction or skills to deal with day to day organisation of living.

Let's all hope that viruses play by the same rules and require RCT and peer review and be considered expert before they can mutate.

My school bubble burst with symptomatic adults. 11 parents decided to randomly test their children. All were positive and asymptomatic (primary). The following week a majority (not all) parents and siblings tested positive. I am assuming asymptomatic children passed it onto family members.

@Lweji

Erm... his whole career is not on infectious disease transmission... And the wrong term is the tell-tale sign of a non-expert.

Do you understand what a pharmacologist does?

I see all sorts of so-called experts dishing out comments about covid. I'd rather read proper articles, preferably articles written not more than a few months ago, when a lot more is known about the disease and its transmission, than from more than a year ago, when it was all very unclear.

Some people just like to get their opinions out, very loudly. It doesn't make them right.

And other people like to search for confirmatory opinions, regardless of who wrote them, and when.

His scientific career...

Ohhh, so you have to be a credentialled epidemiologist to debate/critique scientific papers on matters of disease spread?

"Well, sure, you may indeed have had years of scientific training in a broadly medical field, probably written plenty of research papers and been published too, but as far as I can see, you're only a pharmacist, so your opinion counts for nothing?

To read a paper about asymptomatic spread, to comment on it's conclusions and offer opinion on it's validity, as long as you offer a rationale for your argument, and don't just say 'Well, you're wrong because Chris Whitty says so is the argument from authority fallacy.

Did you even read what he said?

while there are currently uncertainties of various kinds about Whuhan vial pneumonia, better consult with multidisciplinary science team rather than rushing to submit a report.

In other words, 'I think something is up here, perhaps they should consult with other experts to take another look'... But yeah, he's only a pharmacologist, so...

@kellehi - so, who is deciding whether someone is asymptomatic or not? Is it based on patient self-reporting? And what the fuck has been decided are possible covid symptoms, now and what definitely doesn’t count? Would it make you feel better if they expanded the list of possible covid symptoms to pretty much ANY sign of being under the weather, so that everyone who tests positive is likely to be able to say, eg, that they did feel a bit washed out for a day or two, and that counts as a symptom? I feel like I have a slight tickle in my throat at the moment and am sneezing more often than usual. If I test positive, am I symptomatic? How often is someone 100% on top form with no possible symptoms of anything at all? I’m not really seeing the value of presymptomatic v asymptomatic if you aren’t setting any rules on severity, frequency and duration of any possible symptoms, and don’t have any compulsory symptoms that 100% of known positive cases have had.

*Moderna and Pfizer’s mRNA COVID-19 vaccines cut the risk of asymptomatic SARS-CoV-2 infection from 10 days after JUST one dose by 79%.
(investors.pfizer.com/investor-news/press-release-details/2021/Real-World-Evidence-Confirms-High-Effectiveness-of-Pfizer-BioNTech-COVID-19-Vaccine-and-Profound-Public-Health-Impact-of-Vaccination-One-Year-After-Pandemic-Declared/default.aspx)

To clarify, asymptomatic is individuals who have been infected but show no symptoms or a “silent spreader.” This data is pertinent to controlling transmission of this virus. If you can’t infect you can't transmit*

This is a from a molecular biologist.

Presymptomatic spread is not asymptomatic spread. Most papers make that distinction

Nope - totally wrong.

Presymptomatic PATIENTS and asymptomatic PATIENTS are different, although sometimes papers confuse the two and lump them both under asymptomatic. This is commonly done for example with testing results where they declare that x% of people tested were asymptomatic. They mean had no symptoms when tested.

As far as spreading goes, nobody cares whether or not you later develop symptoms. The important thing is that you spread the virus when you don't have symptoms. This was VERY WELL KNOWN from early on last year as there were MULTIPLE cases of asymptomatic superspreaders.

Why do we care about presymptomatic or asymptomatic transmission when the most vulnerable / at risk are vaccinated?
Surely we can't live in fear of something that may or may not happen, this way madness lies.

Yep @kellehi. Makes sense.

The important thing is that you spread the virus when youdon't have symptoms. This was VERY WELL KNOWN from early on last year as there were MULTIPLE cases of asymptomatic superspreaders
Exactly this. They reduced numbers hugely in Liverpool in Oct when they introduced mass community testing and identified asymptomatic spreaders.
My DH was completely asymptomatic and infected me so I know first hand that asymptomatic transmission occurs

What would people have done differently?

Those that think this is important

"His scientific career...

Ohhh, so you have to be a credentialled epidemiologist to debate/critique scientific papers on matters of disease spread?

"Well, sure, you may indeed have had years of scientific training in a broadly medical field, probably written plenty of research papers and been published too, but as far as I can see, you're only a pharmacist, so your opinion counts for nothing?

To read a paper about asymptomatic spread, to comment on it's conclusions and offer opinion on it's validity, as long as you offer a rationale for your argument, and don't just say 'Well, you're wrong because Chris Whitty says so is the argument from authority fallacy.

Did you even read what he said?

while there are currently uncertainties of various kinds about Whuhan vial pneumonia, better consult with multidisciplinary science team rather than rushing to submit a report.

In other words, 'I think something is up here, perhaps they should consult with other experts to take another look'... But yeah, he's only a pharmacologist, so..."

Well, many scientists are more qualified and didn't publish on this just as citation bait.

I'm not saying he is not allowed to speak.
What I'm saying is that the OP shouldn't take his opinion as gospel.
Quite a different thing.

At the time of him writing his opinion, experts were busy doing actual work to figure out what was going on, and then published their findings.
But the OP chose to ignore actual papers written by actual researchers in the field and more up to date information.

But, yes, unless you have specific training to help you decide what to trust, the fact that someone doesn't work in the area should give you at the very least pause for thought before you decide to take their opinion as the only valid or as evidence to back up whatever opinion you have formed from thin air.

@HopelessBlue192

Why do we care about presymptomatic or asymptomatic transmission when the most vulnerable / at risk are vaccinated? Surely we can't live in fear of something that may or may not happen, this way madness lies.

If you mean now, although many are vaccinated, AFAIK most are only with the first dose.

The most vulnerable being the elderly means that the vaccine is less effective, AFAIK, so they are not totally protected.

Besides that, widespread transmission in the community still means that a significant number of people get ill and a large number ends up in hospital. Many young survive because they get good treatment. I know of men my age who got severely ill in hospital and almost died. Imagine they couldn't have access to oxygen or professionals to work on them.

I live in Portugal and we had queues of ambulances for hours outside the hospitals at the last peak in January-February.

You don't want that. So lockdowns.
You don't want lockdowns, so mass testing to keep transmission low all the time. You need low transmission all the time so you need to identify asymptomatic people to keep them from infecting others.

Wuhan managed to test every resident over a period of a couple of weeks. No cases had been reported at that time. They still found infected people. There's a published paper.
That's how far the Chinese government is prepared to go to keep the virus away. And they are largely living normal lives.