Tag Archives: mers

Social Distancing Dashboard

Posted by xaminmo
This site uses anonymous mobile phone data to calculate the change in miles traveled, and the change in number of mobile phone encounters. It is an earlier predictor of how well social distancing is working, without having to wait 12 days for the confirmed cases stats to change, nor worry about changes in testing frequency or methodology.
 
It’s really a green-light instantaneous dashboard kind of thing. They don’t expose trending data, or even numerical data, so you cannot chart, trend, or predict off of this.
 

CV19 no big deal

Posted by xaminmo
A good question I saw and responded to is “Hardly anyone is sick, and hardly anyone has died. Why is everyone all panicky about CV19? What’s missing?”
 
TLDR: It spreads exponentially, and while you have no symptoms. Listen to the experts if you don’t understand. Don’t be a party to manslaughter.
 
NARRATIVE: The missing part is that it’s an exponential spread. It’s like the old puzzle, there’s one lily pad on a pond, and every day, each lily pad becomes two. It takes 30 days to cover the pond. When is the pond half covered? 29 days.
 
Today, the absolute numbers look very mild right now, and that’s what we like. We want them to stay mild, but any action we take will not have an effect for 12 days. Also, number reporting lags by 1 day. 13 days before the end looks like just any other day in paradise. We’re not doubling every day. We’re doubling every 2.2 days.
 
For the US, we are 10 days from overloading hospital capacity, and 14 days from overloading even reserve, crappy capacity. When we overload the hospital capacity, the death rate quadruples. That’s why it became such a panic.
 
Luckily, the declaration of pandemic was on the 11th, which just started to show up in the numbers yesterday. We’ll know by late Thursday if the declaration of national emergency made an impact. The goal is to keep the number of people in the hospital below the threshold where a lot of extra people die. Right now, that looks so far off, but if we didn’t drastically slow the spread, that would start to look grim for the worst survivable cases around April 5, and by April 15 would be just letting the really sick asphyxiate. I say “didn’t” rather than “don’t” because the time to take action has already passed.
 
It’s easy to ignore when 85% of the people infected simply are not counted, and when only 10% of the counted people are at risk of dying from a hospital overload. However, that amounts to 2-5 million people in the US potentially dying from this. With that many, chances are one of them would be a close friend or family member. If it happens to you, then you would definitely care, and you would not care that it was because a bunch of people didn’t understand exponential math.
 
The panic is because a bunch of us care even when it’s not someone close to us, or we can see that it could happen to us. There are a lot of asymptomatic carriers, spreading the disease. So “I feel fine, I don’t need to quarantine” has already lead to deaths, and will lead to many more deaths.
 
It wouldn’t be God’s Will, or bad luck. It would be a willful choice of people to ignore the experts because the non-experts didn’t understand, and therefore decided the experts were not actually experts. Reckless action leading to the death of others is called manslaughter, and negligent action leading to death is called negligent homicide. Purposefully infecting someone would be called murder.
 
Lag times per Feb 7 study in JAMA from Wang et al:
Median time from first symptom to dyspnea was 5.0 days
to hospital admission was 7.0 days
to acute respiratory distress syndrome was 8.0 days.
For survivors, the median hospital stay was 10 days.
https://jamanetwork.com/journals/jama/fullarticle/2761044
 
Lag times per Jan 22 report by China National health:
Median days from first symptom to death were 14 (range 6-41)
70 year old or above (11.5 [range 6-19] days)
below 70 year old (20 [range 10-41] days.
https://onlinelibrary.wiley.com/doi/full/10.1002/jmv.25689?af=R
 
The average is 12 days to show up in the stats, and 20 days start to finish, so that’s what most stats focus on. Policy changes consistently take 12 days to show up in the stats. I’m not sure where that first started, but you can look at the raw numbers and see it. It is self evident.

SARS-2 March 24 Update

Posted by xaminmo

First, the update:

03-24 Tuesday
1-day Projection: WW 425953/18600; PRC 81595/3283; NON 346031/15382; IT 69104/6744; US 57310/731; TX 916/10
Actual Numbers: WW 417966/18615; PRC 81591/3281; NON 336375/15334; IT 69176/6820; US 53740/706; TX 955/12

03-25 Wednesday
1-day Projection: WW 461807/21005; PRC 81686/3288; NON 381238/17782; IT 74856/7654; US 66137/903; TX 1203/16

Infection spread appears to be reducing in US and TX, even though TX was above projections for yesterday.
US shows 134% instead of 135%, and the last 3 days were 130%, 131%, and 123%.
TX shows 135% instead of 147%, and the last 3 days were 108%, 121%, and 126%.

This implies that the declaration of pandemic may have had positive effect.

The numbers from tonight or tomorrow will start reflecting any changes caused by the declaration of national emergency.

Milestones would have pushed out a day, but my methodology was poor. I now show the number for the condition in the left of the note, not the estimated number for that day. Also, I dropped stage 2 here, and just show worst case reserve (smallest number) and best case reserve (largest number). I do not have proper numbers to separate stage 1 (over standard) vs stage 2 (over minimum reserve).

04-05 29k TEXAS ICU OVERRUN STAGE 1
04-06 36k TEXAS VENT OVERRUN STAGE 1
04-10 146k TEXAS ICU STG3
04-11 178k TEXAS VENT STG3 & Hosp STG1
04-14 400k may be the inflection point for Texas
04-15 532k TEXAS HOSP STG3

Milestones are based on guesstimates, because the exact number of ICU beds and placement of ventillators is proprietary data that is hard to find and confirm. My estimates are based on: TX 28.7m pop; 2.9 beds per 1000 in TX (83230); 32% unoccupied (26633) / 11% are ICU (2929); 6.7% ventilators (1787); 10% limited function ventilation (2663) / 5-15% conf need hosp(532k-177k @ overrun); 2-10% ICU (29k-146k); 1-5% need vent (36k-178k)

Testing infrastructure may fail before the inflection point, leading to a false decrease in numbers reported. If that happens, we may not numerically reach the inflection point, which is 60% of the population for R0 of 2.2. Remember, we only confirm 12-15% of the actual cases, as many are mild or even asymptomatic, but are still infectious to others.

I expect these to move further out each of the next few days, and then it will probably look like it levels off a bit for several days before reducing further.

We are not out of the woods. Hospital usage is 1-4 weeks. Average infection course is 20 days with no hospitalization, but once people are bad enough to need O2 or ventilation, it takes longer to recover well enough to not need it anymore.  If we were to fall to 112% today (unrealistic extreme) and stay there, the milestone dates become 04-23, 04-25, 05-07, 05-09, 05-16, 05-18. That spreads out enough that we may gain an extra couple of days on each due to early cases resolving (people do not stay in the hospital forever).

The current milestones for the US, since TX is about 9% of the US:
03-31 29k -> 322k US ICU OVERRUN STAGE 1
03-31 36k -> 400k US VENT OVERRUN STAGE 1
04-05 146k -> 1622k US ICU STG3
04-06 178k -> 1977k US VENT STG3
04-08 400k -> 4444k US inflection point
04-09 532k -> 5800k US HOSP STG 2

These are MUCH more fuzzy, since it is not exactly 9%, and ICU, Vent and bed capacities vary. That adds 1-2 days uncertainty. This also will be affected by any changes in the numbers as discussed above.

Here are the milestones from 04-23 data for comparison to track our progress flattening the curve:
04-06 33k TEXAS ICU OVERRUN STAGE 1
04-07 45k TEXAS VENT OVERRUN STAGE 1
04-10 150k TEXAS VENT/ICU STG2 & Hosp STG 1
04-13 366k TEXAS VENT/ICU STG3 & Hosp STG 2
04-15 660k TEXAS Hosp STG 3

NOTE that the very first milestone was 04-02 based on 570 ICU beds, and was abandoned as a predictor.

When testing and behavior are nonchanging:
Model is +/- 25% per week
That is +/- 1.5 days for stage 1
That is +/- 2.5 days for stage 2
That is +/- 3.5 days for stage 3

Inflection point for R0 of 2.2 is 60%.
Current reporting rate is 12-15%.
Assuming we keep testing by same criteria, the Tx inflection point is 400k confirmed.
We may not reach this numerically due to testing/infrastructure failure.
eg, we may reach stage 3 while our confirmed rate is much lower, but still around the same days.

This is all bistromath, and both reporting rates, and trends are changing daily at this point.

Also note that the numbers lag by up to 24 hours based on reporting systems.

Also Also note that it still takes around 12 days for action changes to affect trends, since people infected today will not be detected for a while.

Also Also Also note that there are many people who have NO symptoms at all, but are still infecting others. This, along with poor testing, explains the 12-15% confirmation rate.

https://drive.google.com/file/d/1vocCN445AZyVBBLsv0kJR8ZDP9DM0UST/view


Overrun Planning

Posted by xaminmo

Stats for Sunday, Monday, and predictions for Tuesday, and Texas hospital overruns.

03-22 Sunday

  • 7-day Projection: WW 262771/11285; PRC 81266/3324; NON 259371/14696; IT 78550/8986; US 25567/280; TX 521/21. plus or minus 25%.
  • 1-day Projection: WW 340729/14895; PRC 81360/3265; NON 260988/11728; IT 61049/5774; US 34015/386; TX 857/5.
  • Actual Numbers: WW 335955/14632; PRC 81397/3265; NON 254558/11367; IT 59138/5476; US 33272/417; TX 627/8

03-23 Monday

  • 1-day Projection: WW 370630/16503; PRC 81489/3271; NON 290297/13301; IT 65275/6215; US 43432/566; TX 627/13. TX Deaths is Still early and erratic
  • Actual Numbers: WW 378287/18600; PRC 81496/3274; NON 296791/13223; IT 63927/6077; US 43667/552; TX 758/9. IT is slowing, which is good. JHU new dataset.

03-24 Tuesday

  • 1-day Projection: WW 425,953/18,600; PRC 81,595/3,283; NON 346,031/15,382; IT 69,104/6,744; US 57,310/731; TX 916/10
  • Actual Numbers: To be determined.  Infection spread for US is fluctuating slightly.

The following major milestones assume no gross change in testing rates nor confirmed infection rates.  Stage 1 is over standard capacity.  Stage 2 is over worst case reserve capacity.  Stage 3 is over best case reserve capacity.  This does not cover additional production, but does cover identified lower-function and out-of-date equipment from federal, military, and major hospital stockpiles.  At Stage 1, alternative locations are getting converted for use by patients, such as closed medical buildings.  At stage 2, we’re relying on medical and nursing students as front-line caregivers, and MASH style pop-up tent hospital expansions start getting deployed where possible. At stage 3, we’re draping parking garages, and getting scouts with first-aid badges to help.  Elderly or anyone with comorbidities will be comforted, but won’t get access to mechanical ventilation.  Only those with the best chance of survival with, and a high risk of death without, would get advanced care.

  • 04-05 33k TEXAS ICU OVERRUN STAGE 1 / 28.7m pop; 2.9 beds per 1000 (83230); 32% unoccupied (26633) / 11% are ICU (2929); 6.7% ventilators (1787) and 10% limited function ventilation (2663) / 5-15% conf need hosp(532k-177k @ overrun); 2-10% ICU (29k-146k); 1-5% need vent (36k-178k)
  • 04-06 45k TEXAS VENT OVERRUN STAGE 1 / 28.7m pop; 2.9 beds per 1000 (83230); 32% unoccupied (26633) / 11% are ICU (2929); 6.7% ventilators (1787) and 10% limited function ventilation (2663) / 5-15% conf need hosp(532k-177k @ overrun); 2-10% ICU (29k-146k); 1-5% need vent (36k-178k)
  • 04-10 150k TEXAS VENT/ICU STG2 & Hosp STG 1 / 28.7m pop; 2.9 beds per 1000 (83230); 32% unoccupied (26633) / 11% are ICU (2929); 6.7% ventilators (1787) and 10% limited function ventilation (2663) / 5-15% conf need hosp(532k-177k @ overrun); 2-10% ICU (29k-146k); 1-5% need vent (36k-178k)
  • 04-13 366k TEXAS VENT/ICU STG3 & Hosp STG 2 / 28.7m pop; 2.9 beds per 1000 (83230); 32% unoccupied (26633) / 11% are ICU (2929); 6.7% ventilators (1787) and 10% limited function ventilation (2663) / 5-15% conf need hosp(532k-177k @ overrun); 2-10% ICU (29k-146k); 1-5% need vent (36k-178k)
  • 04-15 660k TEXAS Hosp STG 3 / 28.7m pop; 2.9 beds per 1000 (83230); 32% unoccupied (26633) / 11% are ICU (2929); 6.7% ventilators (1787) and 10% limited function ventilation (2663) / 5-15% conf need hosp(532k-177k @ overrun); 2-10% ICU (29k-146k); 1-5% need vent (36k-178k)

The inflection point for R0 of 2.2 is 60%. Current reporting rate is 12-15%. Assuming we keep testing by same criteria, the Tx inflection point is about 400k confirmed. We may not reach this numerically due to testing/infrastructure failure. eg, we may reach stage 3 while our confirmed rate is much lower, but still around the same day, and still around the same number of actual infected.  Also, there are different groups between spreaders and isolators.  I don’t know the balance of those two groups. They could be 20/80 or 50/50.

Barring major changes, the model is +/- 25% per week.  That is +/- 1.5 days for stage 1. That is +/- 2.5 days for stage 2. That is +/- 3.5 days for stage 3.

If the Pandemic declaration helped, then 03-24 will be at least 2% low for US and TX. If the Emergency declaration helped, then 03-25 will be at least 2% low for US and TX.  Either of those should show a continual downward trend.  We have had a lot of people ignoring expert and government recommendations, so I do not expect an abrupt change.

If we did abruptly fall to, say, 112% on 03-24 and stay there, then Stage 1 starts April 23-26; then Stage 2 starts May 7-11; Stage 3 may never happen due to average disease cycle of 20 days, and ICU cycle of 30 days.  This would be a dream scenario, and is unlikely.  More likely to see a 5% drop several days in a row.  It’s unlikely to see the clam-down go below 110% until it looks really bad (and then it’s too late).

Texas is about 9% of the US capacity and slightly more capacity than average.  Look for 11x numbers in the US column for similar problems.

  • 33k -> 363k on 03/30 Stage 1 ICU
  • 45k -> 495k on 03/31 Stage 1 Vent
  • 150k -> 1650k on 04/04 Stage 2 / Stage 1 Hosp
  • 366k -> 4026k on 04/07 Stage 3 / Stage 2 Hosp
  • 660k -> 7260k on 04/09 Stage 3 Hosp

112% projections:

  • 112% ICU Stage 1 is 04/10
  • 112% Vent Stage 1 is 04/12
  • 112% V2 / Hosp Stage 1 is 04/23
  • 112% V3/H2 is 05/01
  • 112% H3 is 05/06
  • 112% numbers are +/- 3, 5, and 7 days.

This is all bistromath, and really, anything more than a week out is just guesswork. A lot can change in a week, and I’m expecting substantial changes over the next 3 days based on the activities 10-14 days ago.

The Spreadsheet has been updated. JHU replaced some data sources, so it was a little annoying, and a little more manual entry.

https://drive.google.com/file/d/1vocCN445AZyVBBLsv0kJR8ZDP9DM0UST/view


Projection Spreadsheet

Posted by xaminmo

Google link is https://drive.google.com/file/d/1vocCN445AZyVBBLsv0kJR8ZDP9DM0UST/view View/comment only. I don’t know what broke yet, or if everything works right.


Tsunami

Posted by xaminmo

I have been maintaining projections on omnitech.net/blog and fb.com/xaminmo .

Basically, it is time to hide from society right now. There are a lot of people still spreading it because it is their right to be free. If you get it now, there will be no resources to help you if you get very sick.

Projections may change by Wednesday, since that is 12 days after the national emergency was declared. If we cut our spread in half, then we get almost an extra week of respite.

Except, I know groups of people who were congregating for public meals as recently as Wednesday, and group exercise just Friday. 6 feet at 14mph is not enough. I don’t have the ability to get people to trust me. Either they see, or they don’t. Plenty actively disbelieve. It’s core to their being to believe exactly opposite of me.

We got complacent, because we’re “not like Italy. Look, they are older, and we were infected sooner. We’re so much better, and our death rate is lower.”

Italy started at +25% per day, and brought it down to +12% per day.

The US started at +5-10%, but for weeks has been spreading at +35% per day. Texas, my state, has to do it bigger. We’re spreading at +47%.

So, April 2, Texas ICU reserve capacity is overrun. A week later, all Texas hospital reserve capacity is overrun. I don’t know where in there we run out of trained medical professionals and supplies to treat safely.

If we did a great job when the pandemic was declared, we get 4-6 more days. A week prior, it will look like a normal day, a little busy, and probably still no toilet paper.

I wish it were not so, but the window of opportunity to change this course is almost closed, and we seem to be accelerating towards it, not slowing.

A tsunami is coming, and we have not even felt the tremor yet.


SARS2 not from a lab

Posted by xaminmo

Two bits of info indicating extremely unlikely that this was engineered in a laboratory: A) Computer models show the binding function would be very poor for how it binds; B) The core code of the virus matches animal versions, not versions known to make humans sick.

Here's why: SARS-CoV-2 is very closely related to the virus that causes severe acute respiratory syndrome (SARS), which fanned across the globe nearly 20 years ago. Scientists have studied how SARS-CoV differs from SARS-CoV-2 — with several key letter changes in the genetic code.

Yet in computer simulations, the mutations in SARS-CoV-2 don't seem to work very well at helping the virus bind to human cells. If scientists had deliberately engineered this virus, they wouldn't have chosen mutations that computer models suggest won't work.

https://www.livescience.com/coronavirus-not-human-made-in-lab.html

This evidence for natural evolution was supported by data on SARS-CoV-2’s backbone – its overall molecular structure. If someone were seeking to engineer a new coronavirus as a pathogen, they would have constructed it from the backbone of a virus known to cause illness. But the scientists found that the SARS-CoV-2 backbone differed substantially from those of already known coronaviruses and mostly resembled related viruses found in bats and pangolins.
https://www.scripps.edu/news-and-events/press-room/2020/20200317-andersen-covid-19-coronavirus.html


US must be testing

Posted by xaminmo

Must have been a lot of testing. US count doubled yesterday. Everything except China showed up as higher than projected infection rates. US and TX death rates are still low. Italy death rates are still high. Here are the numebers for 2020-03-19. Today’s numbers release sometime in the next 2-3 hours.

Where     Cases   Deaths  Recovered  Mort/A   Mort/R
World   242,713    9,867     84,962   4.07%   10.41%
China    81,156    3,249     70,535   4.00%    4.40%
NonPRC  161,557    6,618     14,427   4.10%   31.45%
Italy    41,035    3,405      4,440   8.30%   43.40%
US       13,680      200        108   1.46%   64.94%
Texas       260        1          0   0.38%  100.00%

Today’s numbers release sometime in the next 2-3 hours. The estimates for today’s numbers (03-20) are 274102/11148 WW; 81210/3257 PRC; 195048/7975 NON; 47150/3893 IT; 24034/339 US; 391/8 TX

Data source is Johns Hopkins University repository here:
https://github.com/CSSEGISandData/COVID-19/tree/master/csse_covid_19_data/csse_covid_19_time_series

Projections are just Excel, divide today by yesterday to get the change day to day, then use a 7-day average to guess what tomorrow might be, and do that again for each row.

In the US, first and second hand reports show that people are tested for seasonal influenza first, and if they test positive, they are not tested for SARS-2. This is conserve the the limited number of tests. It’s less likely for people to have both COVID19 and influenza at the same time. This may change as testing capability increases. According to Trump, Rosche, Quest, Labcorp, and Wal-Mart may be rolling out rapid testing capability starting in April.

In the US, it looks like the confirmed cases are about 13% of the actual infected. The actual death rate for non-overwhelmed places tends to be about 4.5% of the confirmed cases, when there’s ~14% testing (PRC and WW average).

The real mortality rate will therefore be that much less, which puts it in the same order of magnitude as seasonal influenza, but without the ability for people to get vaccinated, and a higher infection rate due to longer infectious incubation period.


0317 Projection Update

Posted by xaminmo

Estimate for today was within 1% again, except Italy was 2% lower on both infections and deaths. That is two days of increasingly lower rates than projected. GOOD JOB ITALY! Their March 22 numbers are on track to be less than the original 1week projection. Death rates are still high, at almost 8%. It’s hard to bring that down, especially since their population is 9 years older than the US, China, South Korea, etc.

The US has been consistently higher than projections. Authorities won’t test for COV19 if you test positive for influenza first. It’s likely the US reporting rate is less than the 14% that China had. On March 22, the US will be higher than the original 1week projection. Death rates are at 1.68%, which is suspiciously low. I am concerned that perhaps deaths are being attributed to other things, or testing is being avoided so that the stats look better. It could also be a new strain of the virus, but I would think that would get a lot of promotion from the government.

I’m having a discrepancy between World vs PRC + nonPRC, with WORLD going high. This may be a random error, but I’m wondering if China’s +30/day is false information. They have kicked out foreign press, and are in a propaganda war with the White House over who’s at fault. The difference is bigger than I would expect could come from the US’s reporting anomalies.

Because of reporting deficiencies, the real number infected is 6-8x the formal numbers, and that typically equates to about a week into the future as a SWAG for real but unreported cases. If you are still going out of the house with non-family members for recreational purposes, you are being selfish, and are a menace to society. If you are doing so to provide essential services, then please be extra careful.

Some of you may have noticed that, if the detection rate is only 14%, then that means the mortality rate is also a sixth of what we think. Yes, but it still spreads too fast, and the absolute numbers of people needing hospital care to survive still would overwhelm hospitals, leading to much higher death rates. So, even if the mortality rate is a flat 0.5% for everyone under age 64, and hospitalization needs are still only 2%, we still need to flatten the curve. At the current rate, and assuming 14% reporting rate, the US is on track to have the whole population infected in one month, with 6 million needing hospital care, and about a million needing external ventillation. We have about a million beds, and about 100k ventillators, with another 60k of old and less effective types. Also, if everyone is sick, who can be the caregivers?

Projections for tomorrow are WW 214086/8769; 81083/3243 PRC; 134076/5591 Non-PRC; 35476/2903 IT; 8901/137 US; 142/1 TX. I think we can expect the US to be 1-2% above projection, and Italy 1-2% below projection. Texas should have additional deaths any day now, but both TX and the US are still tracking substantially lower death rates than expected. I’m hoping to see a slow-down for the US next week. It seems a lot of people got the message for today, and have been reducing their out-of-house socializing.


Projections for 03/17 and 03/22

Posted by xaminmo

I run an infection rate projection based on the last 7 days change rates using the JHU case data stats which are updated around 18:30 Central/US each day (vs 04:00 Central/US for the WHO data).

For Monday, 03-16, it was generally within ~1%:

World projection was 179621 confirmed and 7127 dead.
World actual was 181546 confirmed and 7126 dead.

China projection 81029 / 3213.
China actual was 81033 / 3217.

Non-China projection 99472 / did not project dead.
Non-China actual was 100513 / 3909

US Projection 4490 / 74.
US Actual was 4632 / 85.

TX Projection was 91 / 1.
TX Actual was 85 / 1.

For 03/17-18:30ish projections, I have:
Est: WW 196830/7885 ;
PRC 81063/3231;
NonPRC 116869/4721;
IT 31635/2574;
US 6132/115;
TX 100/1 though at low numbers, dead could be 1-6.
For 1 day, I’d expect to be within 2% on any of these numbers.

Note that the real-time trackers are not exactly aligned with this data, and the covid19info.info page I like so much is using a different data source for China, or has not refreshed from the formal stats. They do not match JHU nor WHO, but the other data matches. I’m thinking maybe they run a projection instead of real stats, and need to add newer datapoints.

Also note that Italy and China’s death rates are higher than the US, and higher than the world minus China. If it were just the US, then I would say maybe it’s affluence, or testing anomalies. Instead, I’m thinking that Italy had China’s first strain, and that perhaps the rest of the world has a secondary strain of the virus? I don’t really have the tools, skills, nor time to analyze the gene sequences to build a CV19 family tree to confirm this.

I don’t expect to see a change in the overall growth rates until sometime next week. Pandemic declaration was on the 11th, so Monday the 23rd will probably start to show a dip, plus or minus a day, depending on how much social distancing is actually happening, and when people started. Plenty are still ignoring, or selectively ignoring. I know I ordered food, and the family went to grab things from the university dormitory. Plenty of public facing workplaces still are interacting with unscreened, unlimited people.

For Sunday the 22nd, I’m expecting 262771/11285 worldwide; 81266/3324 China; 259371/14696 non-PRC; 78550/8986 Italy; 25567/280 US; 521/21 Texas. The US numbers could be higher if the two hot zones overrun their hospital capacity, or if a new hot zone pops up. 7 days is a long time, so let’s say it could be plus or minus 25%.

If you want to be safe, then remember that most incubation is under 14 days. People who have self-quarantined for 14 days can co-mingle with other people who have self-quarantined for 14 days and be at very low risk. The longest incubation on record was 27 days, so groups or mutual 27-day self-quarantine would be ultra-low risk. There’s never a zero risk, since there will invariably be one or two asymptomatic carriers. Also, anyone who lies, or anyone who breaks these rules will potentially be a vector for infection into that entire cluster of people. Self-quarantine means no contact outside of a closed group. I’m not sure the increased risk from food deliveries, well-spaced grocery store visits, etc. (Did the cook dip their glove in your food accidentally after scratching their face? Did the stock crew at the store have someone not safe? Did you disinfect the outside of the packages you got in the mail?).