Down-the-line Covid exposure contact tracing--

[Kev Williams]

Since the FDA and CDC can't seem to get it together, I thought I'd consult the experts!

flowchart:

1 is contagious
2 contacts 1 last Thursday (5 days ago)
3 contacts 2 Friday
4 contacts 3 Saturday, football game
5 contacts 4 Sunday, family visit
6 and 7 in contact with 5 on Monday AND Tuesday

Questions: When does a 'merely' exposed person become contagious? What's the likelihood 5, 6 and 7 have actually contracted the virus?

--Guess who 6 and 7 are--

[roger wiegand]

Once you get to 3-4 contact circles out you're talking everyone in the country. If I were 2 I'd watch carefully for symptoms, stay isolated, and get tested if possible. Three and beyond have a pretty good chance of having been exposed to someone who has been exposed to someone no matter what.

I can't quite fathom why we haven't embraced two bits of technology that could have brought this to a halt by now, one an antigen-based rapid diagnostic test that every person in the country could be taking every day they need to leave the house (based on other RDTs should cost about dollar each or so to make), and, two, a $50 powered respirator (put up a billion dollar prize for its development and deployment) for those who find masks too uncomfortable, distributed free to everyone who needs one. Even if each measure is only 80% effective on its own, combined with reasonable social distancing and hygiene the three combined would give a 99% reduction in transmission. Even if each is only 50% effective it would reduce transmission by nearly 90%, which should do the trick. Yes it would cost a few tens or even hundreds of billions to implement and inconvenience some people; what we are (not) doing now is costing trillions and being incredibly destructive.

Then of course there's the issue of getting folks to care enough about their family, friends, and neighbors to take on these simple measures without turning it into political theater. That one is not so readily solved.

[William Chain]

Souls 2 and 3 should be isolated, and beyond that will depend on exposure - masked/unmasked, duration of exposure, etc.

Casual exposure (e.g., passing in a hallway) is not high risk. Sitting at football game next to one another for over 10 minutes of common air space is high risk. Precisely why that kind of thing is discouraged or cancelled right now.

You'll have to make the call. If you are in a vulnerable group, I'd isolate for 14 days and see.

I've isolated twice now due to careless coworkers. It does suck, but it's necessary.

[Curt Harms]

I think Roger is correct on most counts. Having a relatively accurate at-home test, or perhaps take the sample at home and drop it off at your local pharmacy would encourage more widespread testing. Make it clear that a positive test could be a false positive are not a death sentence, just an indicator to get a more accurate test. This whole thing has been PBARd (politicized beyond all recognition) which unfortunately will probably cost lives.

[Stan Calow]

any or all those people could be exposed to other infected people during the surveillance period.

[Jim Becker]

S
Questions: When does a 'merely' exposed person become contagious?

Simple question and simple answer: They become contagious if and when the virus infects them. The incubation period for COVID-19 is 2-14 days, more or less.

[Bill Dufour]

If #2 is not sick by now you are probably okay. Of course they could be young and asymptomatic. They really should open up college campuses and let the young ones get sick and recover before going home at break. Allow only students who do not live at home to be physically on campus. Of course the staff does not like that idea. All those old rich professors will get sick and many will die and lose their tenure or emeritus. This policy would cause fewer deaths then drafting them and sending them to Vietnam or Afganistan.
Bil lD.

[Dennis McGarry]

https://www.nytimes.com/2020/08/29/h...irSliHsUcJCXfM

[mike stenson]

You don't have to be young to be asymptomatic. Also, the young aren't completely immune to long term illness and consequences. Some of the people I've known who ended up being the sickest were in their 20s.. so far.

So much mis(dis)information.

[Kev Williams]

thanks all--

to update the info-
1 is known to be positive, not necessarily contagious, but I'm taking that for granted anyway-
Everyone but 1 is asymptomatic, and I'm not even sure if 1 is--
2, 3 and 4 are teenagers or pre-teens-
I assume 2 and 3 have been tested but not clear on that yet.
4 is my BIL's grandson, he was tested Tuesday, results Friday-
5 is my BIL who works with us.
6 and 7 are the wife and I-

The BIL and I have been within 2' of each other, side to side unmasked, probably 3 times in 2 days, for no more than 1 minute while he was watching and listening to me while I was setting up his laser jobs. which is normal. He spoke very little if at all best I recollect. Only rarely do we ever speak face to face, when we do talk we're usually at least 10' away. The past few days is no exception. He's only here about 5 hours a day. The wife's main exposure is to me. We all share the front and garage door knobs and the basement stairs handrail. Aside from the laser setups we've been separated by at least 10' or more almost constantly, which is normal...

Because we're a business we have hand sanitizer galore and masks are worn by all when customers are present. We also have several cans of disinfectant spray and Clorox disinfectant hand-sprayer cleaners. EVERYTHING that comes into this house, groceries, mail, packages, PO's, customer parts, even cash, gets sanitized. The BIL is staying home until he hears any test results of those above us in this chain, which I hope is sooner than later. I'm going to see if I can locate a place that does rapid tests and get myself checked today.

I'll be collecting my first SS payment any day now. Last thing I need is to be a victim of the 'retirement curse'. 'Specially since I'm not retired yet!

[Andrew Joiner]

Once you get to 3-4 contact circles out you're talking everyone in the country. If I were 2 I'd watch carefully for symptoms, stay isolated, and get tested if possible. Three and beyond have a pretty good chance of having been exposed to someone who has been exposed to someone no matter what.

I can't quite fathom why we haven't embraced two bits of technology that could have brought this to a halt by now, one an antigen-based rapid diagnostic test that every person in the country could be taking every day they need to leave the house (based on other RDTs should cost about dollar each or so to make), and, two, a $50 powered respirator (put up a billion dollar prize for its development and deployment) for those who find masks too uncomfortable, distributed free to everyone who needs one. Even if each measure is only 80% effective on its own, combined with reasonable social distancing and hygiene the three combined would give a 99% reduction in transmission. Even if each is only 50% effective it would reduce transmission by nearly 90%, which should do the trick. Yes it would cost a few tens or even hundreds of billions to implement and inconvenience some people; what we are (not) doing now is costing trillions and being incredibly destructive.

Then of course there's the issue of getting folks to care enough about their family, friends, and neighbors to take on these simple measures without turning it into political theater. That one is not so readily solved.

Thank you Roger! Your professional experience is valued here. I've been thinking the same thing.
Not sure anyone who find masks uncomfortable would wear a powered respirator, but yes great ideas.
How about a recommended standard for masks? Sure any face covering is better than nothing. A leaky, droopy mask or bandana is less effective and just as uncomfortable as the best masks.

I finally settled on KN95 masks. Best comfort and protection.

[roger wiegand]

I think the current work suggests that N95s and surgical masks are both about equally effective (and quite good). N95s with relief valves are less effective for protecting bystanders, aerosol droplets easily escape out the valve. Cloth masks are less effective but way, way better than nothing (and may be better than a valved N95 for protecting others). In a situation where I knew I was going to be exposed to an infectious person I'd double mask with a surgical mask over an N95 (lots of docs who see sick patients are doing this), changing the outer surgical mask between patients.

I don't go out much, but I use a well made cloth mask thats big enough to pretty well cover my beard (and my big nose). There's still a national shortage of N95's so I will leave them for folks on the front lines for now. In MA at this point I think our numbers are such that you have to be both unlucky and doing something wrong to pick up an infection in a "normal" socially distanced community setting. Mask compliance here is close to 100%. I'm comfortable with the cloth mask in that setting. We'll see how that changes as all the students return.

How about a recommended standard for masks? Sure any face covering is better than nothing. A leaky, droopy mask or bandana is less effective and just as uncomfortable as the best masks.

I finally settled on KN95 masks. Best comfort and protection.

[Stan Calow]

...How about a recommended standard for masks?

Faces are too non-standard to have a perfect mask.

[Kev Williams]

, and, two, a $50 powered respirator [...], distributed free to everyone who needs one.

https://www.hammacher.com/product/el...upplement-2020

Not hardly free and not sure of it's actual usefulness...

[roger wiegand]

https://www.hammacher.com/product/el...upplement-2020

Not hardly free and not sure of it's actual usefulness...

That one doesn't filter both incoming and outgoing air, so wouldn't meet my design criteria.

I'm thinking something like my old AirMate helmet, but a *lot* less clunky and lighter weight, with a push/pull airflow system that filters both ways and allows the wearer to not have a mask close to their face. It should run for >2h on a charge, have interchangeable batteries for longer use, charge on a USB charger, and have filters that can be sterilized in a pressure cooker or dunked in 10% bleach. If we can build an iphone how hard could this be?

And after COVID all the woodworkers could breathe a lot less sawdust.