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

How would you prove asymptomatic transmission anyway?

@dementedpixie

How would you prove asymptomatic transmission anyway?

That's one of the difficulties I alluded to in my post, but I'm sure they'd have worked it out by now...

Good thread, since most of the school threads on here were freaking out on the basis that asymptomatic transmission was huge. I haven't seen any hard evidence for it. Any paper, scientist or even WHO representative that has dared question it has quickly reversed their opinion or had their papers removed from the public domain.

Why? Who knows?

Maybe because they realised that the issue would arise again when they declared vaccines a success because they prevent the spread by reducing symptoms. Because it's hard to spread droplets if you ain't coughing or sneezing which is the main reason asymptomatic spread simply can't be as big a factor as some would have had us believe.

Quite astonishing that we have to dig people's brains out with a cotton swab to find it when it floats so easily from person to person on the ether.

What is your point?

Research that is a year old, might as well be 50 years old, it's really outdated as far as this is concerned.

Quite astonishing that we have to dig people's brains out with a cotton swab to find it when it floats so easily from person to person on the ether

Your scientific knowledge astounds me yet again 🙄🙄🙄

@WitchesBritchesPumpkinPants

Quite astonishing that we have to dig people's brains out with a cotton swab to find it when it floats so easily from person to person on the ether

Your scientific knowledge astounds me yet again 🙄🙄🙄

It's probably more extensive than you realise.

Is it not the case that like most viruses the host is most infectious in the days prior to symptoms developing? So although that is different from someone who never develops symptoms it's still asymptomatic spread and is pretty much the case with most viruses.

I know it was one of the things Chris Witty and Boris said they wished they had known about earlier - it was one of their regrets about things done wrong/too late, along with having way understimated the speed of the inital spread.

So there is obviously some evidence that it exists, if only by exptrapolation. But it's one of thoise things that will be REALLy hard to research, gather evidence, especially given the rush to vaccinate.

From last December www.bmj.com/content/371/bmj.m4851

www.bmj.com/content/371/bmj.m4851

This is interesting

@dementedpixie snap!

@WitchesBritchesPumpkinPants

What is your point?

Research that is a year old, might as well be 50 years old, it's really outdated as far as this is concerned.

My point is that one of the earliest research studies analysing a case study for asymptomatic transmission of the new virus called Covid-19 in the German index case has had the authors concluding that the patient was asymptomatic when in fact she was clearly not. She may have had comparatively mild symptoms, but she was definitely symptomatic.

TL;DR - one of the first studies used to base the principle of asymptomatic transmission on was actually nothing of the sort.

Especially as asymptomatic transmission is something which was never found to exist for any other virus previously to Covid-19

The early proof was from a super-spreader event in Korea, where two people without symptoms went to church, and caused an outbreak

They became symptomatic shortly afterwards, so I suppose there is a question of terminology over asymtomatic and pre-symptomatic.

But the TL:DR version is that people without symptoms can spread it, and they can spread to large numbers of people.

Set against that the role of the K number - why do some infect no-one or very few and very close only, and why do others spread it readily to many?

@Alittlelouder

Is it not the case that like most viruses the host is most infectious in the days prior to symptoms developing? So although that is different from someone who never develops symptoms it's still asymptomatic spread and is pretty much the case with most viruses.

No. Presymptomatic spread is not asymptomatic spread. Most papers make that distinction.

We are trying to distinguish between people who it is said go about spreading the disease without knowing it, vs people who wake up one day feeling a bit ropey, but still good to go, and then four days later they are flat on their back and all their contacts are starting to feel a bit rough too

But we do know that you can spread covid before your symptoms start.

Oh no! That's bad science! A thing not having been identified previously isn't evidence of anything! CV-19 is novel in many ways!

Mistakes get made, that report was not from a completed study, as with everything else at that point it was first impressions of a novel virus. We were told many things that turned out to be inaccurate, but that doesn't mean the science should not have happened. It also doesn't mean the research into transmission should stop looking at any possible factor.

@UnmentionedElephantDildo

The early proof was from a super-spreader event in Korea, where two people without symptoms went to church, and caused an outbreak

They became symptomatic shortly afterwards, so I suppose there is a question of terminology over asymtomatic and pre-symptomatic.

But the TL:DR version is that people without symptoms can spread it, and they can spread to large numbers of people.

Set against that the role of the K number - why do some infect no-one or very few and very close only, and why do others spread it readily to many?

Not asymptomatic. Asymptomatic are people who NEVER develop symptoms...

@Northernsoullover

But we do know that you can spread covid before your symptoms start.

That sounds likely and similar to other viruses but not the same as asymptomatic spread.

@CuriousaboutSamphire

Oh no! That's bad science! A thing not having been identified previously isn't evidence of anything! CV-19 is novel in many ways!

Mistakes get made, that report was not from a completed study, as with everything else at that point it was first impressions of a novel virus. We were told many things that turned out to be inaccurate, but that doesn't mean the science should not have happened. It also doesn't mean the research into transmission should stop looking at any possible factor.

Yes I know. Just like people believe they can achieve cold fusion, but they haven't managed it yet. It doesnt mean that cold fusion is inachievable. But it doesn't mean that it is either...

The early proof was from a super-spreader event in Korea, where two people without symptoms went to church, and caused an outbreak

They became symptomatic shortly afterwards, so I suppose there is a question of terminology over asymtomatic and pre-symptomatic.

Yes, this is a very important distinction I think. They think that someone is most infectious just before they start symptoms (so when they are 'asymptomatic') and just when symptoms begin.

But this is different to someone who never shows any symptoms - are these people ever actually infectious?

No. Presymptomatic spread is not asymptomatic spread. Most papers make that distinction. Yes! As there can be an overlap, again early data that helps map how the two are understood

wwwnc.cdc.gov/eid/article/26/7/20-1595_article

Yes I know. Just like people believe they can achieve cold fusion, but they haven't managed it yet. It doesnt mean that cold fusion is inachievable. But it doesn't mean that it is either... You do know that makes no sense?! If you use that as your reasoning for anything you just wouldn't get out of bed!

Not asymptomatic. Asymptomatic are people who NEVER develop symptoms... Ah! I see. You are using the ABSOLUTE definitions rather than any real world observations that might help understand the spread of covid!

OK!

www.nature.com/articles/d41586-020-03141-3

"Although there is a lower risk of transmission from asymptomatic people, they might still present a significant public-health risk because they are more likely to be out in the community than isolated at home, says Andrew Azman, an infectious-disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, who is based in Switzerland and was a co-author on the study. “The actual public-health burden of this massive pool of interacting ‘asymptomatics’ in the community probably suggests that a sizeable portion of transmission events are from asymptomatic transmissions,” he says.

But other researchers disagree about the extent to which asymptomatic infections are contributing to community transmission. If the studies are correct in finding that asymptomatic people are a low transmission risk, “these people are not the secret drivers of this pandemic”, says Byambasuren. They “are not coughing or sneezing as much, they’re probably not contaminating as much surfaces as other people”.

Muge Cevik, an infectious-disease researcher at the University of St Andrews, UK, points out that because most people are symptomatic, concentrating on identifying them will probably eliminate most transmission events."

jammi.utpjournals.press/doi/10.3138/jammi-2020-0030

"Results: We screened 2,454 articles and included 13 low risk-of-bias studies from seven countries that tested 21,708 at-risk people, of which 663 were positive and 111 asymptomatic. Diagnosis in all studies was confirmed using a real-time reverse transcriptase–polymerase chain reaction test. The asymptomatic proportion ranged from 4% to 41%. Meta-analysis (fixed effects) found that the proportion of asymptomatic cases was 17% (95% CI 14% to 20%) overall and higher in aged care (20%; 95% CI 14% to 27%) than in non-aged care (16%; 95% CI 13% to 20%). The relative risk (RR) of asymptomatic transmission was 42% lower than that for symptomatic transmission (combined RR 0.58; 95% CI 0.34 to 0.99, p = 0.047). Conclusions: Our one-in-six estimate of the prevalence of asymptomatic COVID-19 cases and asymptomatic transmission rates is lower than those of many highly publicized studies but still sufficient to warrant policy attention. Further robust epidemiological evidence is urgently needed, including in subpopulations such as children, to better understand how asymptomatic cases contribute to the pandemic."

@Juliesipadwillcallyouback

The early proof was from a super-spreader event in Korea, where two people without symptoms went to church, and caused an outbreak

They became symptomatic shortly afterwards, so I suppose there is a question of terminology over asymtomatic and pre-symptomatic.

Yes, this is a very important distinction I think. They think that someone is most infectious just before they start symptoms (so when they are 'asymptomatic') and just when symptoms begin.

But this is different to someone who never shows any symptoms - are these people ever actually infectious?

Please...

Asymptomatic means that you NEVER get symptoms.

Presymptomatic means that they do develop, i.e you are most infectious when you aren't quite feeling 100% but several days before your sore throat/fever/aches and pains etc develop

You don't turn from asymptomatic into symptomatic. 'just before you start symptoms is not 'when they are asymptomatic. It is when they are presymptomatic...

@CuriousaboutSamphire

Not asymptomatic. Asymptomatic are people who NEVER develop symptoms... Ah! I see. You are using the ABSOLUTE definitions rather than any real world observations that might help understand the spread of covid!

OK!

It is a very important distinction actually. If someone is 'asymptomatic', never transmits disease and we only know they have covid in the first place by using unreliable testing then the whole house of cards comes down.