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  COVID-19 Transmission and Children
Posted by: M_T - 08-18-2021, 01:31 AM - Forum: Research - Replies (1)

The journal research brief behind the current news can be found at the American Academy of Pediatrics site
"Association of Age and Pediatric Household Transmission of SARS-CoV-2 Infection"
(Free sign-in required to access full article)
And, separately,
Commentary:  "Yes, Children Can Transmit COVID, but We Need Not Fear"
WebMD coverage:  "Youngest Kids More Likely to Spread COVID-19 to Family: Study"

From the shortened version of the paper on the web site:

Quote:Results: A total of 6280 households had pediatric index cases, and 1717 households (27.3%) experienced secondary transmission. The mean (SD) age of pediatric index case individuals was 10.7 (5.1) years and 2863 (45.6%) were female individuals. Children aged 0 to 3 years had the highest odds of transmitting SARS-CoV-2 to household contacts compared with children aged 14 to 17 years (odds ratio, 1.43; 95% CI, 1.17-1.75). This association was similarly observed in sensitivity analyses defining secondary cases as 2 to 14 days or 4 to 14 days after the index case and stratified analyses by presence of symptoms, association with a school/childcare outbreak, or school/childcare reopening. Children aged 4 to 8 years and 9 to 13 years also had increased odds of transmission (aged 4-8 years: odds ratio, 1.40; 95% CI, 1.18-1.67; aged 9-13 years: odds ratio, 1.13; 95% CI, 0.97-1.32).


But, don't just stop with that paragraph.
From the actual paper (PDF)

Quote:Results:  Between June and December 2020, a total of 6280 private
households had a pediatric index case (Figure1).  The mean (SD)
age of index case individuals was 10.7 (5.1) years and 2863
(45.6%) were female individuals. Of 6280 households,
1717 (27.3%) experienced secondary household transmission,
leading to a median of 2 secondary cases (25th percentile,
1 case; 75th percentile, 2 cases; 90th percentile, 3 cases).
This corresponded with an overall crude rate of transmission
of 27 341 per 100 000 households with pediatric index cases.
Pediatric index cases most frequently transmitted infection to
individuals aged 0 to 20 years or 30 to 50 years, with older chil-
dren tending to transmit to older individuals in those age ranges
(Figure 2).
The proportion of index cases in each age group
increased with age, with 12% (776 of 6280) aged 0 to 3 years,
20% (1257 of 6280) aged 4 to 8 years, 30% (1881 of 6280)
aged 9 to 13 years, and 38% (2376 of 6280) aged 14 to 17
years (Table 1). Compared with index case indivudals in the
oldest age group, younger index case individuals had a
higher proportion associated with a school/childcare out-
break and shorter testing delays. Index case individuals aged
4 to 8 years and 9 to 13 years had higher proportion with no
symptoms reported compared with index case individuals
aged 14 to 17 years or aged 0 to 3 years. Across all age groups,
more index case individuals had disease onset in the fall/
winter (September-December) compared with the summer
(June-August), which aligns with the trajectory of the sec-
ond wave of the pandemic in Ontario.


So, the headlines are that infants infect others in the household more.  That's in the results in the web site but NOT mentioned in the results of the paper itself (but is in the discussion).   That is just one side of the elephant.

Another side is that the older children bring home COVID more often than younger children.
Index cases:  0-3: 766;  4-8: 1257;  9-13: 1881; 14-17: 2376

"Of 6280 households,
1717 (27.3%) experienced secondary household transmission,
leading to a median of 2 secondary cases (25th percentile,
1 case; 75th percentile, 2 cases; 90th percentile, 3 cases)."


Unfortunately, this neglects to tell us how many members were in the households.  Are these primarily 1 parent & 1 child household, or 2 parent & 10 children households?  Are they infecting virtually everyone or virtually no one in the household?

"This corresponded with an overall crude rate of transmission
of 27 341 per 100 000 households with pediatric index cases."


I'm going to have to figure out what they are saying there.

"Pediatric index cases most frequently transmitted infection to
individuals aged 0 to 20 years or 30 to 50 years, with older chil-
dren tending to transmit to older individuals in those age ranges
(Figure 2)"



Well, duh!  To me, their figure 2 bubble plot (age of secondary infected case vs age of index infected case) just shows the ages within families based on the age of one child taken at random.  It obviously shows 3 groups: siblings, parents&aunts/uncles, grandparents.  (At index age 17, it appears children of the index case (or niece/nephew) are starting to show up.)

The proportion of index cases in each age group
increased with age, with 12% (776 of 6280) aged 0 to 3 years,
20% (1257 of 6280) aged 4 to 8 years, 30% (1881 of 6280)
aged 9 to 13 years, and 38% (2376 of 6280) aged 14 to 17
years (Table 1)


The older the children are, the more likely they are to be the one to bring COVID into the house.  Again, they left out vital statistics indicating the Toronto population of children in each age group (note the age groups span 4, 5, 5, and 4 years).  So the rate of index cases (per population) is apparently much higher in the 14-17 than in younger ages, which makes sense as they have more social interactions and often ignore the rules. The (apparent) under-detection of asymptomatic cases in 14-17 suggests an even higher rate of that age group bringing the infection home.

Compared with index case indivudals in the
oldest age group, younger index case individuals had a
higher proportion associated with a school/childcare out-
break and shorter testing delays.


Yes, the oldest age group had more socialization, while the social interactions in the younger groups are more often just school.

 Index case individuals aged
4 to 8 years and 9 to 13 years had higher proportion with no
symptoms reported compared with index case individuals
aged 14 to 17 years or aged 0 to 3 years. 


No surprise here.  Ever try to get a mid-teenager or late-teenager to do anything, like take a COVID test?   Especially if one outcome will mean they are grounded for 10 days.   If you're the parent of a 0-3, you're probably frazzled and don't have resources to take them in for a test unless it is really bad (as happened in my extended family).   So, reduced testing, and thus detection, under no-symptom situations is not surprising to me.  Thus, you should expect a higher proportion of no-symptom positive tests reported in the more manageable adolescent years.

Across all age groups,
more index case individuals had disease onset in the fall/
winter (September-December) compared with the summer
(June-August), which aligns with the trajectory of the sec-
ond wave of the pandemic in Ontario.


Chicken and egg....  Let me rephrase it to give an equivalent expression:  The trajectory of the second wave in Ontario aligned with the detected pediatric index cases, showing more cases while school was in session.

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  What % of infected are hospitalized
Posted by: M_T - 08-12-2021, 07:57 PM - Forum: COVID-19 - Replies (3)

The American Assn of Pediatricians gives weekly numbers for COVID in children.  Their numbers are extracted from the states' public data, and of course each state does it differently.  What counts as children may be ages 0-17, 0-18, 0-19, or 0-20.
Children and COVID-19: State-Level Data Report

Among their data was a state-by-state breakdown of what percent of children's cases resulted in hospitalization.  I thought this was a useful number to know, so I calculated it from the CDC tables by dividing
hospitalizations/100K for age group in last week  by
cases/100K for age group in last week

These numbers are likely to be low because cases are climbing and hospitalizations lag behind cases.  But it is a first crack at it.
From:
https://covid.cdc.gov/covid-data-tracker...csovertime
https://gis.cdc.gov/grasp/COVIDNet/COVID19_3.html

Week ending  7/31/2021
Age   Wk Cases/100K  Hosp/100K    Hosp/Cases
 0-4    59.8         1.2         2.0%
 5-11   84.8
         0.4         0.5%
12-15   96.4
         
12-17 ~104.5         0.7         0.7%
16-17  120.8
18-29  157.9         2.7         1.7% 
30-39  146.7         5.5         3.7% 
40-49  120.2         7.0         5.8%
50-64   84.1         8.3         9.9%
65-74   59.3         9.6        16.2%
75+     52.4       ~13.7        26.1%
75-84               12.7
85+                 16.3


Because the age ranges were different, I had to calculate some of the numbers from others, indicated by "~"

I find these numbers surprisingly high.  Ok, maybe 26% of 75+ have to be hospitalized.  That seems dramatic.  But one out of 6 cases in the age group 65-74 have to be hospitalized?  One out of 10 cases in 50-64?  One out of 200 K-6 student cases?  (Remember, they aren't vaccinated)

The average size of a primary school in the US is 442 (in 1999-2000).  If COVID burns through all the unvaccinated students, an average of 2 will need to be hospitalized.

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  California wimpy school COVID requirements
Posted by: M_T - 08-11-2021, 04:37 PM - Forum: COVID-19 - Replies (2)

I just reviewed California's rules on schools & COVID and I'm supremely disappointed. 

August 11, 2021 order
June 11, 2021 order
COVID-19 Public Health Guidance for K-12 Schools in California, 2021-22 School Year (dated Aug. 2, 2021)


 They require ONLY

1. Students & adults wear masks indoors.  (A non-adult visitor is not required to wear a mask.)
2. COVID cases are reported to the state and local public health departments.
3. School system workers (incl. unpaid; limited to adults) have vaccinations or else get tested weekly (with tests that include those with 50% false negative rates).

That's it.

Students (and non-employee adults) ARE NOT required to quarantine if they've been exposed, nor required to isolate if they've been diagnosed.   Employed teachers may be required to quarantine only if some other regulation requires it.

Nor are they required to get tested or stay home if they have symptoms.
Students (etc.) that have been diagnosed with COVID are not required to stay out of school, nor are they required to be separated from other students.
Students (etc.) that show up at school obviously sick are not required to be separated from other students nor required to be sent home.  There's no wording that suggests that schools have a plan for this situation.

Eating is allowed indoors.  No minimum separation required.
Cleaning is not required (relative to COVID), only recommended (and even then, once a day is all that is recommended).
Contact tracing by the school is only a "should have a plan" recommendation.

"Safe distancing" is specifically excluded from being recommended.


Specifically, the California State Health Officer's orders do not require anyone to do anything if a student is diagnosed with COVID and comes to school anyway, nor can anyone do anything if a student is obviously sick with COVID and does not take a test.  I see nothing that gives the school and requirement to protect the other students.   Presumably, such a student would not be contact traced (unless the parents reported the COVID test while still sending their child to school).  The local Health Departments might contact the school if they knew of the test result, but they are not required to do so by the State's orders.

AFAICT, the state nowhere requires those diagnosed with COVID to isolate, except in their role as an employee.  (and, of course, the CDC doesn't either).  I guess it is all up to the local health departments.

No wonder the US has so much trouble with COVID.

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  Santa Clara County (CA) stats
Posted by: M_T - 08-10-2021, 02:57 PM - Forum: COVID-19 - Replies (2)

Using my home county as an example, from their COVID data.

Reported cases (per 100K unvax) in unvaccinated is running roughly 4x reported cases (per 100K Jax) in vaccinated.  That gives a vaccine effectiveness of 75%.  That ratio has been holding steady.

Total cases per 100K (of the specific age population):
0-1      4,200 per 100,000.
2-7      3,400 to 3,700
8-9       4,000
11-13   4,500
14-15   5,000
16       5,700
17      6,700
< 19   4,775
20-29 10,000
30-39   8,100
40-49   6,800
50-59   6,000
60-69   4,700
70-79   3,500
80-89   4,300
90+     8,000

These numbers are before school starts exposing kids to each other.

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  Could this scenario happen?
Posted by: M_T - 08-09-2021, 12:46 PM - Forum: COVID-19 - Replies (1)

Consider this image from Pfizer
[Image: E7esN_zUcAgXTV0?format=jpg&name=medium]

Note that the protection against Beta has almost disappeared (compared to pre-vaccination).

Imagine if Delta runs through the unvaccinated as it is doing.  Suppose all those unvaccinated get infected, and the survivors thus have a natural immunity.  The vaccinated have a waning protection against other variants but suppose the vaccines last well enough so that the vast majority are protected for this wave of Delta.

But, suppose that the vaccinated's protection against Beta is negligible in, say, November.  Couldn't a wave of Beta spread through the vaccinated, just like Delta spread through the unvaccinated?  (Maybe Beta doesn't have quite the infectibility of Delta, so the spread wouldn't be as dramatic)

It would be ironic (and seen as support for those antivaxers that survived) if there were a wave of COVID that primarily went through those with early vaccinations?

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  Tidbits
Posted by: M_T - 08-07-2021, 10:04 AM - Forum: COVID-19 - Replies (1)

I found these articles from Science interesting
8/4  "What does the Delta variant have in store for the US? We asked coronavirus experts"
Reactions and behavior are changing too fast to make good predictions.

8/5  "A giant trial of COVID-19 treatments is restarting.  Here are the drugs it's betting on"


An issue with COVID is that we are still early in its evolution.  There are uncountable numbers of variants that are possible.  (I haven't heard anyone doing massive simulations to detect dangerous variants before nature does.) The rest of our lives may be spent fending off variants every year or so.   It seems people, perhaps with government & media encouragement, think this is a one-time blip, and they can't be bothered with it interfering with sports & entertainment & dining out.

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  Pfizer half-life 3 months (65-85yo); 3rd booster boost
Posted by: M_T - 08-05-2021, 11:59 AM - Forum: Vaccine - Replies (2)

From an image in Pfizer's late-July investor's report:
with notation added by Michael Lin:
[Image: E7esN_zUcAgXTV0?format=jpg&name=medium]

For 18-55yo, the decrease in neutralizing titers for wild & beta variants matches a half life of 3 months (so reduce by a factor of 16 in a year).

I calculate a half-life of 3.1mo for 18-55 and 2.2mo for 65-85.
That's a yearly drop in neutralizing titer by a factor of 15 for 18-55 and a factor of 44 for 65-85yo.

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  Affect of vaccines on viral load
Posted by: M_T - 08-05-2021, 11:42 AM - Forum: Research - No Replies

Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine-breakthrough infections: a multi-center cohort study"
(Usual warnings about preprints)

From Michael Lin's twitter feed (taken from above paper)

[Image: E7uDITgWEAUQzoj?format=jpg&name=medium]

Basically this shows the viral load is equal in vaccinated & unvaccinated for the first 6 days.  That's the dangerous time before you realize you are sick.

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  Current testing
Posted by: M_T - 08-05-2021, 11:23 AM - Forum: COVID-19 - No Replies

An unvaccinated (child) relative is traveling within the US.  By CDC recommendations, an unvaccinated traveller should both get tested  before & after travel, AND quarantine (presumably after each leg of travel).

So, I looked into testing for when you don't have but a few days until travel.  Just FYI, this is what I came up with (personal details removed).  YMMV (pun intended).  Different locations may have different situations.

"Both vaccination and previous infection can result in a positive antibody test."
I believe you can do the antigen tests (less sensitive).
This news report indicates one survey found antigen got 41% of the PCR detected infections.
(Here is a medical paper on diagnostic tests.)
(Here is a site that evaluates all the tests.)

========
CVS minute clinic is offering 1-2 day PCR tests plus antigen and antibody tests.   All testing requires an appointment.
https://www.cvs.com/minuteclinic/
Perhaps only some sites are set up for the full suite of tests.

CVS Home tests:
Pixel PCR:  Out of stock near you
BinAx (See below at Walgreens)  In stock at your location.   71x 5 star reviews; 10x 1 star review.
Ellume  In stock nearby.  26x 5 star reviews; 43x 1 star reviews.  Lots of false positives reported.

----------
Costco Pharmacy offers a home test(saliva PCR $115 - $119), with results quickly after receipt by the lab.
Your Costco isn't listed.  The nearest listed is .....
https://www.azova.com/costcotravel/?prim...l_id=35918
Drop off completed test before UPS pick-up Thursday and expect results
FRI to SUN 
12 - 48 HRS
The claim is " This test has a sensitivity of 98% (meaning 98% of positive tests are correct) and a specificity of 99% (meaning 99% of negative tests are correct)."

There is a version of this test ($20 more?) in which they will observe you doing the test by video.  This might be useful to avoid someone claiming you faked the test.  (The intent of observation is to validate the test for travel.)


=======
Walgreens offers free drive-up testing
ID-Now rapid test (24 hrs) or PCR lab tests.
(It appears ID-NOW is a high quality 15-minute test, rivaling PCR, but clearly they aren't evaluating it in the store)
https://www.walgreens.com/findcare/covid19/testing?ban=covidfy21_newtestingpg_heroban
(Aegis testing turnaround: 6 hours after it gets to the lab.
Labcorp testing turnaround: 1-2 days (as of June 30)

Walgreens also offers at-home testing with no lab required

BinaxNow:  $24 for two tests for one person.  In stock at Encinitas and Oceanside
Abbott  BinaxNOW COVID-19 Antigen Self Test should be performed twice in 3 days, at least 36 hours apart.
647x 5 star, 62x 1 star reviews
  Shallow Nasal swab
Independent testing:  88% detection of positives.  99% detection of negatives.
But another study showed much worse detection:  64% detection of symptomatic patients; 35% detection of asymptomatic.

Quote:Why is this test indicated for “serial testing” and what does serial testing mean? Serial testing means that people should test themselves frequently, so that if they’re positive, they can catch themselves at the beginning of their infection and, hopefully, before they transmit it to others. By having our test indicated for serial testing, it offers an added layer of protection. That’s why each box comes with two tests in it.
My reading is:  Serial testing is required because the first test may miss the infection and your chances are much higher if you test twice to NOT get two false negatives.

QuickVue  $24 for two tests for one person.   In stock nearby.
 Shallow Nasal Swab
Reviews show some kits were damaged.  Some report of false positives.  62x 5 stars, 24x 1 star reviews

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  CDC document re Delta
Posted by: M_T - 07-30-2021, 07:37 AM - Forum: COVID-19 - No Replies

The Washington Post apparently acquired a copy of a CDC document dated Thursday July 29.  A slightly redacted version can be found at their site:
"Improving communications around vaccine breakthrough and vaccine effectiveness"

This contains some not yet published material (thus marked "confidential"), as well as a good summarization of the available data.

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