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Covid19 not as easy to transfer as currently thought? - Printable Version

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RE: Covid19 not as easy to transfer as currently thought? - magnus - 04-14-2020

Here's an old study that seems apropos

https://www.ncbi.nlm.nih.gov/pubmed/18556606

Claims that for respiratory infections, handwashing with our without antibacterial soap only reduces transmission by about 21%.

So cloth masks (someone here posted it reduces by 25%?) is better than handwashing? =)

RE: Covid19 not as easy to transfer as currently thought? - oldalum - 04-14-2020

(04-12-2020, 03:33 PM)M T Wrote:  Why lower?  
Because she directly touched a surface without protection that seconds or minutes earlier had been touched by another person's hand, then she presumably didn't wash her hands when she came in. Can't think of a more likely fomite transmission, unless the neighbor had coughed onto her hands and then carried the bags to her door. 

She picked up the mail every several days, so much of it had been sitting there for hours to days, and had been put there by a postman wearing gloves (which can certainly be contaminated, but less likely to touch your face with gloves on or cough onto the gloves).

My impression is that the thinking on fomite transmission is that it's less easy than previously thought, hence the title of this thread and the comments above that fomite transmission is uncommon.

But YMMV. It's all speculation on our part.

RE: Covid19 not as easy to transfer as currently thought? - M T - 05-08-2020

(04-12-2020, 03:03 AM)magnus Wrote:  Well,  this news bit is the opposite of this thread topic. 

https://www.wcnc.com/mobile/article/news/health/coronavirus/charlotte-woman-hasnt-left-her-house-in-three-weeks-but-tested-positive-for-covid-19/275-77707b1d-fd2f-4a36-bf3e-16beca4104c4

A woman who hasn't left her house in 3 weeks tested positive for coronavirus.   She does live with her husband (though separate room) and had groceries delivered once (apparently delivery person later tested positive).  Source of transmission unclear.

Update on this:
https://www.wcnc.com/article/news/health/coronavirus/charlotte-woman-hasnt-left-her-house-in-three-weeks-but-tested-positive-for-covid-19/275-77707b1d-fd2f-4a36-bf3e-16beca4104c4
(Alert: same link, updated content).

Symptoms appeared Mar 22.  Groceries delivery was Mar. 20.  Trip to pharmacy was Mar 18.
The article now says an epidemiologist claims it was a keypad at the pharmacy.  Why that rather than the door handle, a shopping basket, a credit card or cash handed back to her, or the air at the pharmacy, isn't said.  Unless they have video of someone with Covid-19 coughing into their hand and then using the keypad, I don't know how they could pick one thing over the others.  (Presumably groceries were discounted as 2 days is very low for incubation time.)

RE: Covid19 not as easy to transfer as currently thought? - magnus - 05-08-2020

(05-08-2020, 11:52 AM)M T Wrote:  
(04-12-2020, 03:03 AM)magnus Wrote:  Well,  this news bit is the opposite of this thread topic. 

https://www.wcnc.com/mobile/article/news/health/coronavirus/charlotte-woman-hasnt-left-her-house-in-three-weeks-but-tested-positive-for-covid-19/275-77707b1d-fd2f-4a36-bf3e-16beca4104c4

A woman who hasn't left her house in 3 weeks tested positive for coronavirus.   She does live with her husband (though separate room) and had groceries delivered once (apparently delivery person later tested positive).  Source of transmission unclear.

Update on this:
https://www.wcnc.com/article/news/health/coronavirus/charlotte-woman-hasnt-left-her-house-in-three-weeks-but-tested-positive-for-covid-19/275-77707b1d-fd2f-4a36-bf3e-16beca4104c4
(Alert: same link, updated content).

Symptoms appeared Mar 22.  Groceries delivery was Mar. 20.  Trip to pharmacy was Mar 18.
The article now says an epidemiologist claims it was a keypad at the pharmacy.  Why that rather than the door handle, a shopping basket, a credit card or cash handed back to her, or the air at the pharmacy, isn't said.  Unless they have video of someone with Covid-19 coughing into their hand and then using the keypad, I don't know how they could pick one thing over the others.  (Presumably groceries were discounted as 2 days is very low for incubation time.)

Thanks for the update, MT.  
So what we also learned is that "hasn't left the house in 3 weeks" while true, is misleading, because the original article didn't mention that she got her first symptoms 2.5 weeks prior (or 4 days after she last left her house).
Well, regardless, it's good to hear she survived.

RE: Covid19 not as easy to transfer as currently thought? - oldalum - 05-08-2020

just amazing if she wears gloves to pick up the mail but didn't wear gloves into the pharmacy.


thanks for the update

RE: Covid19 not as easy to transfer as currently thought? - akiddoc - 05-08-2020

(04-10-2020, 05:13 AM)baymeadows3408 Wrote:  
(04-09-2020, 09:28 PM)Goose Wrote:  
(04-09-2020, 07:45 PM)BostonCard Wrote:  Exactly.  Paradoxically, what makes SARS-COVID-2 so dangerous is that it does not cause universally severe disease.  The advantage that public health officials had in fighting SARS, MERS, and Ebola is that it was easy to identify who was sick and who was contagious.  Fighting Covid-19 is like being in a sea of icebergs.  For each case you see at the surface, there are several under the water that you can't see.


BC
Amen! These cases may not show symptoms for 2-3 days while they are spreading the disease. If the subject doesn't get real sick, they may not notice and spread the disease for weeks.

I'm in grad school right now so I can become a speech-language pathologist, and I have concerns about how my future job might put me in danger. SLPs tend to work in hospitals (close contact with sick people for things like swallowing evaluations), schools (known breeding grounds for disease), and in speech clinics (kids and adults coming in and out all day and having kids touch materials). The clinician and the client need to be able to see each other's faces for things like articulation therapy. I've had kids cough directly onto me. I'm not going to be comfortable doing this kind of work until A) there's a vaccine B) there is rapid testing to prove that the person I'm working with is not an asymptomatic carrier C) there is a treatment that makes COVID-19 less heinous if you do contract it or D) we have overall herd immunity, but it looks like I may not be comfortable for a while.

In my job, I basically get coughed on every day of the year. Or at least the equivalent. Kids touching my face with saliva covered hands. Sneezing on me. Crying at me with a wide open mouth. I'm going to be really interested in the infection rate among Pediatricians. Many have not been working for two months, but things seem to be picking up.

RE: Covid19 not as easy to transfer as currently thought? - stupac2 - 05-08-2020

(05-08-2020, 07:50 PM)akiddoc Wrote:  In my job, I basically get coughed on every day of the year. Or at least the equivalent. Kids touching my face with saliva covered hands. Sneezing on me. Crying at me with a wide open mouth. I'm going to be really interested in the infection rate among Pediatricians. Many have not been working for two months, but things seem to be picking up.

My kid just turned four, which means he's due for some shots. We were really negligent about scheduling an appointment, which worked out fine all things considered. We currently have an appointment scheduled for a month or so from now, I'm really curious to see how they're going to manage this. Maybe by then we'll be doing in-person visits, idk. Given that my wife is due in July we'll be interacting with the healthcare system no matter what, although at least we had planned a home birth from the beginning this time around. (Apparently our midwives got inundated with calls in March. Go figure.)

RE: Covid19 not as easy to transfer as currently thought? - M T - 05-10-2020

(05-08-2020, 07:50 PM)akiddoc Wrote:  In my job, I basically get coughed on every day of the year. Or at least the equivalent. Kids touching my face with saliva covered hands. Sneezing on me. Crying at me with a wide open mouth. I'm going to be really interested in the infection rate among Pediatricians. Many have not been working for two months, but things seem to be picking up.

On Friday, someone, unofficially (hence "someone"), indicated the infection rate (ever infected, not currently infectious) of tested staff at a Bay Area hospital was less than 1% (offered as a counterpoint to the Stanford antibody study).

I've been thinking about the prevalence of the infectiousness for someone you come across in Santa Clara County.  Currently, every day, about 1 in 100,000 people in SCC test positive. Each case is infectious and not in quarantine for about 5 days (a few days before symptoms + a few days after symptoms before realizing you are really sick).   So, about 1 in 20,000 people you might run into is infectious. If the 1 in 100K are all symptomatic, and if there is as many new asymptomatic cases as new symptomatic, and we assume the asymptomatic are infectious for 10 days, then 1 in 6,700 people are infectious.    That's all back-of-the-envelope, rough calculations.

RE: Covid19 not as easy to transfer as currently thought? - BostonCard - 05-10-2020

OSU is doing this study, by going around Corvalis and measuring the prevalence of COVID-19.

https://www.statesmanjournal.com/story/news/2020/05/08/oregon-state-university-testing-estimates-2-1000-corvallis-residents-have-coronavirus-covid-19/3097984001/

They found a prevalence of COVID-19 of 2/1000 (since they sampled 455 people, it means one of them was positive).  That would predict a crude 95% confidence interval around the prevalence of .006% to 1.2%.  Note however, that this is not strictly correct, because they sampled households, so there is a bit of a correlation structure.

Also, for what it is worth, the county (Benton) has reported 44 cases of COVID-19 in a county with 93,000 residents, which is a known case rate of 0.5/1000, and 5 deaths.

BC

RE: Covid19 not as easy to transfer as currently thought? - Snorlax94 - 05-11-2020

F
(05-10-2020, 05:02 PM)M T Wrote:  On Friday, someone, unofficially (hence "someone"), indicated the infection rate (ever infected, not currently infectious) of tested staff at a Bay Area hospital was less than 1% (offered as a counterpoint to the Stanford antibody study).

I've been thinking about the prevalence of the infectiousness for someone you come across in Santa Clara County.  Currently, every day, about 1 in 100,000 people in SCC test positive. Each case is infectious and not in quarantine for about 5 days (a few days before symptoms + a few days after symptoms before realizing you are really sick).   So, about 1 in 20,000 people you might run into is infectious. If the 1 in 100K are all symptomatic, and if there is as many new asymptomatic cases as new symptomatic, and we assume the asymptomatic are infectious for 10 days, then 1 in 6,700 people are infectious.    That's all back-of-the-envelope, rough calculations.

I ponder the same question when I go out, but I come up with a more pessimistic number if I use your approach. Assuming your # days infectious and ratio of symptomatic/asymptomatic are correct, your calculations assume 100% of symptomatic people eventually are tested and reflected in confirmed cases, but I think there are still many mildly symptomatic people who are never tested. Early on, who knows, maybe only 1 in 10 or 1 in 60 symptomatic people were getting tested because there were too few tests. SCC is still trying to set up more testing sites to reach more of the population, still trying to get more test supplies, and still hasn’t communicated clearly how everyone will get tested, how it will be paid for, where to go, etc. My guess would be still only 1 in around 5 symptomatic people in SCC are getting tested, that’s just a guess. I’d assume we are testing a much higher percentage of actual infections now because the % positive for tests used to be around 10% in SCC and now looks to be under 2%.

But if we’re only testing and confirming 1 in 5 symptomatic infections, maybe closer to 1 in 1,000 people are infectious, assuming the rest of your numbers are right. But I think that is a very scary way to look at things. It’ll hopefully convince people not to stand in a packed arena shoulder to shoulder with strangers for hours, but in everyday situations, even if 1,000 shoppers and joggers pass nearby every 10 days, it’s extremely unlikely that 1 puff of breath is going to get someone sick. Plus you’d hope not all the symptomatic people are the ones going out.

Here’s another way to crunch SCC’s  numbers that comes up with a sunnier picture: if only 1 in 100,000 people in SCC get sick enough to get tested per day, you could go 200 days with the current case counts and you’d have only a 1 in 500 random chance of getting sick enough to end up getting tested (or, a 99.8% probability of not getting sick enough to be a confirmed case). And the daily case counts in SCC are dropping — hopefully the average for the next 200 days will be only 1/10 or 1/20 the current rate. So hopefully, in SCC maybe the odds will be 99.98+% you can avoid getting sick enough that you’d test positive during the next 200 days, assuming we can drive the case counts low and keep them low even during a partial reopening.  But then, flu season will be here...

RE: Covid19 not as easy to transfer as currently thought? - M T - 05-11-2020

(05-11-2020, 03:40 AM)Snorlax94 Wrote:  SCC is still trying to set up more testing sites to reach more of the population, still trying to get more test supplies, and still hasn’t communicated clearly how everyone will get tested, how it will be paid for, where to go, etc.

SCC Public Health Department's testing page seems pretty clear.  Contact your primary care physician.  If you don't have one, or don't have insurance, contact Valley Medical Center.   They list about 13 different health organizations and give their basic info.  The County of Santa Clara Health System lists 4 drive-through locations (M-F mornings).  Stanford Healthcare lists 3 drive-through locations.  They list 15 (+ 2 future) other testing locations.  Call for info for PAMF, Kaiser, RMC/Good Samaritan, ECH, VA Palo Alto.

The guidelines for who should get tested was updated on May 2. 
Anyone If capacity allows, This does bring up an issue.  SCC's numbers show number of tests.  It does not show test results for unique individuals.  Suppose a grocery store requires their employees to be tested weekly.  They may test as negative week after week, and stop being tested if they become positive.   So SCC's testing numbers may not show what I wish it would show.

RE: Covid19 not as easy to transfer as currently thought? - fullmetal - 05-11-2020

Fomite-based transmission was the hypothesis after observing infection patterns aboard cruise ships, iirc.  I see no reason to doubt that fomites can be the method of transmission based on those observations, unfortunately.  

The case of the isolated/distanced woman contracting the virus from her grocery deliverer is worrisome as people have been echoing the theory that outdoor air circulates and dilutes aerosol risk down to negligible amounts (and that sunlight kills the virus, yay /s).  I have refrained from jumping into that fray.

Anyway, although patients are generally poor historians, examples like this serve to remind everyone to be vigilant about who is near you and who may be asymptomatically contagious.

RE: Covid19 not as easy to transfer as currently thought? - Snorlax94 - 05-11-2020

(05-11-2020, 10:27 AM)M T Wrote:  This does bring up an issue.  SCC's numbers show number of tests.  It does not show test results for unique individuals.  Suppose a grocery store requires their employees to be tested weekly.  They may test as negative week after week, and stop being tested if they become positive.   So SCC's testing numbers may not show what I wish it would show.
Yes, unfortunately, We can’t assume the most symptomatic 800-1500 people are being tested each day in SCC.

For example, a doctor at Sutter Health told me *every* patient coming in for a procedure is tested, which makes sense. But if 200 people a day are coming in for medical procedures across all their facilities, and none of them are positive, it can make the county’s stats look better than they may be.

I understand that there are guidelines of when to get tested, and that people are supposed to contact their PCP first, but I’d argue, still, many many symptomatic people are not being tested. While I may have a PCP and specialist that I’ve been seeing for years for every one of my needs, many of my middle-aged friends don’t even have a PCP and never get physicals. When I was young, I didn’t have a PCP. And while I read news regularly and frequently research where to get what, I wonder whether my gardener or housecleaner would be able to easily get tested. I see a way better system in LA where anyone can get a test, they have a website where any LA resident can sign up, and the LATimes continually lists all the testing locations. I’d argue SCC and the Bay Area can make things a lot easier. It needs to get to the point where the slacker 25 year old version of me could roll out of bed one day, have a fever, and easily scoot in to get tested that day with minimal effort. Or even a version of my 25 year old slacker me that didn’t speak English.

RE: Covid19 not as easy to transfer as currently thought? - stupac2 - 05-11-2020

(05-11-2020, 05:21 PM)fullmetal Wrote:  Fomite-based transmission was the hypothesis after observing infection patterns aboard cruise ships, iirc.  I see no reason to doubt that fomites can be the method of transmission based on those observations, unfortunately.  

The case of the isolated/distanced woman contracting the virus from her grocery deliverer is worrisome as people have been echoing the theory that outdoor air circulates and dilutes aerosol risk down to negligible amounts (and that sunlight kills the virus, yay /s).  I have refrained from jumping into that fray.

Anyway, although patients are generally poor historians, examples like this serve to remind everyone to be vigilant about who is near you and who may be asymptomatically contagious.

The thing is that something being rare doesn't mean it's impossible. The thing about fomite transfer is that degrees matter, shaking hands is obviously stupid, but how much does it matter if you touch an object someone else touched? Touch sometime that someone else touched, then touch a different object, then wash your hands, then touch the second object again? At some point the transfers start to be immaterial.

Same thing with outdoor exposure, it obviously could happen if that jogger who just ran by is sick, but I'd be far more worried about just standing in the grocery store for an hour.

RE: Covid19 not as easy to transfer as currently thought? - magnus - 05-20-2020

CDC now says virus not easy to spread from surfaces. 

https://www.foxnews.com/health/cdc-now-says-coronavirus-does-not-spread-easily-via-contaminated-surfaces

Question,  does this also apply to handshaking?  If so,  no more elbow bumps!  (Err once social distancing goes away)

RE: Covid19 not as easy to transfer as currently thought? - burger - 05-20-2020

(05-20-2020, 12:27 PM)magnus Wrote:  CDC now says, without any new evidence, virus not easy to spread from surfaces. 

https://www.foxnews.com/health/cdc-now-says-coronavirus-does-not-spread-easily-via-contaminated-surfaces

Question,  does this also apply to handshaking?  If so,  no more elbow bumps!  (Err once social distancing goes away)

Fixed that for you.  Or is there some new evidence about surfaces that I haven't seen?

This is so wishy-washy as to be useless (from the relevant CDC page):

Quote:It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes. This is not thought to be the main way the virus spreads, but we are still learning more about this virus.

The CDC guidelines have been watered down by political interference from the Trump administration.  They're all but useless.

RE: Covid19 not as easy to transfer as currently thought? - Snorlax94 - 05-20-2020

(05-11-2020, 07:29 PM)stupac2 Wrote:  
(05-11-2020, 05:21 PM)fullmetal Wrote:  Fomite-based transmission was the hypothesis after observing infection patterns aboard cruise ships, iirc.  I see no reason to doubt that fomites can be the method of transmission based on those observations, unfortunately.  

The case of the isolated/distanced woman contracting the virus from her grocery deliverer is worrisome as people have been echoing the theory that outdoor air circulates and dilutes aerosol risk down to negligible amounts (and that sunlight kills the virus, yay /s).  I have refrained from jumping into that fray.

Anyway, although patients are generally poor historians, examples like this serve to remind everyone to be vigilant about who is near you and who may be asymptomatically contagious.

The thing is that something being rare doesn't mean it's impossible. The thing about fomite transfer is that degrees matter, shaking hands is obviously stupid, but how much does it matter if you touch an object someone else touched? Touch sometime that someone else touched, then touch a different object, then wash your hands, then touch the second object again? At some point the transfers start to be immaterial.

Same thing with outdoor exposure, it obviously could happen if that jogger who just ran by is sick, but I'd be far more worried about just standing in the grocery store for an hour.
+1

RE: Covid19 not as easy to transfer as currently thought? - magnus - 05-27-2020

And we're back to staying cautious of surface transfers.

https://www.foxnews.com/health/cdc-warns-may-be-possible-coronavirus-spread-surfaces

Quote: In its statement, the CDC said it's possible to contract COVID-19 from touching a surface or object that has the virus on it and then touching your face, adding: "The primary and most important mode of transmission for COVID-19 is through close contact from person-to-person."

The edit comes after the agency initially said Wednesday that the virus “does not spread easily” by “touching surfaces or objects"


RE: Covid19 not as easy to transfer as currently thought? - magnus - 06-11-2020

Some positive news from Missouri

The "salon" (does anyone consider Great Clips a salon?) that had 2 hairstylists with confirmed Covid serving a combined 140 customers has received word back that none of the 40 some-odd people tested came back positive and none of the remaining customers. who apparently all went into a 2 week quarantine, showed any signs of Covid-19.

https://www.cnn.com/2020/06/11/us/missouri-hairstylists-coronavirus-clients-trnd/index.html

If you want to argue the findings, I guess you can say that the 90-100 that didn't get tested could have been infected and just been asymptomatic.

Still, no symptoms is better than some symptoms.
Oops, snorlax94 already posted the above newsbit in the covid attitudes thread.

I'll leave it up rather than see a "Deleted message" note.