Asymptomatic transmission extremely rare

[James]

I’m sure the usual suspects will say they meant pre-symptomatic.

https://www.bbc.co.uk/news/health-52977940

[matt123]

This usual suspect has been carefully writing “asymptomatic or pre-symptomatic” In their posts for a long time. I’m sure you can dig some out where I don’t; over qualifying everything becomes a bore.
The key points being that:
There has been widespread evidence published by the medical community of transmission by people without symptoms since February.
What matters is that a person without symptoms can be infectious. The link you have posted clears up that most of these people are pre- not a-; it doesn’t change the fact that lots of Infected people without symptoms can be infections
It’s great that we now know people who remain asymptomatic aren’t very infection, but it changes nothing about our government’s ignorance of the multiple highly credibly sources of evidence from many different studies in February and March that people without symptoms were spreading the virus. What it does do is give me hope that testing and contact tracing is going to be making more difference.

[Bill]

What matters is that a person without symptoms can be infectious. The link you have posted clears up that most of these people are pre- not a-; it doesn’t change the fact that lots of Infected people without symptoms can be infections

Does it?
In England, the Office for National Statistics (ONS) has been regularly testing a sample of the population.
It has found that, of those who have so far tested positive for Covid-19, only 29% reported “any evidence of symptoms” at the time they were tested, or at the previous or following visits.
The language is ambiguous but I presume we take ‘those who have so far tested positive’ to be only those in the ONS study and positive since most PHE/NHS testing has so far been of quite sick people. To me that implies a high fraction (71%) are and remain genuinely asymptomatic and I only say implies rather than confirms because the timing of and rigour of the follow-up regime isn’t discussed but ONS aren’t motivated cowboys. Am I misreading that because it seems remarkable and at odds with plenty of other good quality studies.

[steve]

It’s kind of misleading. Pre-symptomatic/asymptomatic is essentially the same thing.
Basically an otherwise healthy kid in the classroom could suddenly cough and infect those kids at his table, or in any other situation.

[bert]

This sparked some controversy and it looks like the WHO have kind of redacted the statement by saying ‘more research is needed to answer it’. Details in this thread from Obama’s head of healthcare:

NEW: The WHO made a surprising announcement that asymptomatic people w COVID rarely spread it.

I’ve talked to 4 reputable scientists, the White House, and the WHO.

I believe this was an irresponsible statement even though it was based on legitimate observations. Thread here.1/

— Andy Slavitt @ 🏡 (@ASlavitt) June 8, 2020

[Bill]

I’m sure the usual suspects will say they meant pre-symptomatic.

What do you mean? As someone who’s still rather puzzled by and regularly questioning of the huge spread of values reported for the asymptomatic fraction of CV cases I guess I’m one of the ‘usual suspects’. I don’t know what you’re getting at.
It’s interesting if the vast majority of cases genuinely are asymptomatic and pose a low transmission risk but as ever there are so many wildly disparate reports, often from credible institutions putting the asymptomatic case fraction anywhere between 3% and 80% that either we’re missing something really interesting about the disease or our use (and acceptance) of imprecise language to report technically limited studies.

[Author]

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