Spurned by a click-bait article I saw in my news feed, I searched for "covid-19 asymptomatic transmission rare" and found references to a WHO conference where this seems to have been said.
A few links in, I found the WHO Periscope video from which this information has been shared.
A lot of other discussion goes on, and each bit tries to point out that this is still serious, and that we're better prepared, but that the virus is still spreading, and that we must continue being careful. All as expected, with some seemingly agenda-less information shared, and kudos to places doing well.
Getting on in the meeting, about 32 minutes in (also on YouTube), Emma Farge, from Reuters, asks specifically about asymptomatic transmission, calling out reports of no documented cases of this. Dr Maria Van Kerkhove answers with a discussion about information tracking and contact tracing, but she does confirm the rarity of asymptomatic transmission.
Of particular interest, she points out that these asymptomatic patients are being found by contact tracing, and that following these contacts they aren't finding secondary transmission. She actually says "it is very rare."
The screen-shot shows the (typo-containing) closed-caption text where, at 34m48s, she says "it still appears to be rare that an asymptomatic individual actually transmits onward." She repeats this again at 35m25s. Their transcript puts this a few seconds earlier.
She does outline different levels of "asymptomatic," including those actually with mild symptoms, and makes mention that the documentation or reporting is unclear, too. She also calls out the source of these are from contact tracing, so while they do have the virus, they may not have developed it to the point of being contagious.
What she doesn't say is that asymptomatic people don't transmit the disease, just that the documentation is not there. And that they want to continue to focus on those that are symptomatic, and trace their contacts, test and quarantine and treat appropriately.
What would it mean if asymptomatic people didn't transmit the disease? It removes some of the scare. But only barely. A big part of the scare is that you can unknowingly contract this virus, by passing through exhalation or touching something infected by someone who didn't know they were contagious. That person, surely, would have been responsible enough to avoid others if they were symptomatic, but since they likely also contracted it from someone who was not symptomatic, they also thought they were safe.
If you need to be symptomatic to transmit the disease, it's likely much easier to ease the restrictions. Of course, that's a lot of trust in people to self-diagnose and self-isolate until they can be tested. If they can be tested. And then to continue in isolation until the tests can confirm either way.
That one little cough...do we pay attention to it? Was it just a little phlegm or spittle or dust? Was it related to an irritant or allergen? Or was it the first indication or a subtle dryness that will become a full-fledged symptom. What about that one-degree uptick in temperature? Would you even notice? Would you think maybe it was because of other natural reasons? How do you know the shortness of breath is real, and not a little allergy or irritant blockage, or because of a moment of exertion?
It'd be great if asymptomatic people didn't transmit the virus. We need to be certain our testing and acceptance of the results are broad, accurate, and comprehensive. The laser thermometers, probably not a bad start. The easy swab (not the deep nasal probe) needs to be nearly immediate.
I'd queue, socially distant and wearing a mask, outside my office to be measured and swabbed, and then wait for a rapid result. I'd go home or seek medical treatment if my test came back positive for the virus or antibodies, as would surely be directed. I'd go into my office feeling pretty safe, and work with social distance and a mask, if my test came back positive.
We've been really good about staying home, leveraging drive-up, drive-through, or delivery for our needs and wants. The times we've had to enter stores, it's been with separation and masks, without touching anything we didn't need to, usually holding and using a disinfectant wipe, and interacting as little as possible, shopping as quickly as possible. We've stuck to our neighborhood, apart from our neighbors, not interacting closely, when we do have a need for an outside break. We've sat on our deck or porch more in the last few months than in the years since they were built. I'm pretty confident I don't have it.
But maybe I'm asymptomatic.