Thread by @Loretta_Torrago

This CDC presentation of yet-to-be-published data shows kids:
* transmit as efficiently as adults
* are infected at rates similar to adults.
It's not getting the attention it deserves perhaps because it's only available as video. I've done my best to faithfully transcribe it.🧵

"If you do not look for children outside of universal studies, you are probably going to miss them.

From various studies, when testing systematically for children exposed to SCV-2, children are as likely to have infection detected as adults.

However, one caveat to consider is that the risk of exposure for children relative to adults has changed dramatically during the course of the pandemic. For example, at the start of the pandemic a full societal shutdown likely benefitted children more than adults .....

..... meaning it reduced exposures for children more than for adults.

This pattern of kids relative to adults has likely changed when society reopened, when schools reopened which changed the risk for children.

We now have studies w/strong methods that account for differences in exposure & include universal testing. W/in these studies, we are seeing children transmitting SCV-2.

Now I want to review some important and fairly new data with you. This data is from The Coronavirus Household Evaluation and Respiratory Testing Cohort Study. This is a study of households that includes children less than 18.....

Individuals in the cohort participate in weekly surveillance testing for SCV-2 infection. In addition to weekly testing ... they respond to weekly inquiries about whether they have had any illness or symptoms that meet a Covid-like illness case definition.

In addition to weekly screens .... individuals also collect an additional swab at the onset of any Covid symptoms. All the viral testing is done via RT-PCR. This slide shows that incident rates of SCV-2 infection per 1,000 person weeks by age group overall & at each site.

As you can see here, incident rates were similar across the age groups at both sites and overall among the cohorts as indicated. ...

Whereas the last study I described was a cohort study, this is a case ascertained household transmission study in which lab confirmed SCV-2 index cases and all household contacts are enrolled to assess secondary infection rate.

The top of the table on the left shows the age category of the ... first case in the household to develop illness or to test positive. The number of total household contacts are also shown in the fist column. The second column shows the secondary infection rate.

In general, the top part of the table captures transmission risk from various age categories. As you can see, secondary infection rates for primary cases ages 0-4 was 46%. The secondary infection rate for household members where the primary case was 5-11 years, was 64%.

The 3rd column & graph on the right shows the risk ratio of 2ndry infection rates for each age group relative to the reference group ...18-49 yr olds.

As you can see, there is not a statistical difference btw 2ndry infection rate for children primary cases relative to adult primary cases.

The bottom part of the table captures age of contacts and their secondary infection rates somewhat analogous to the last study we described and as you can see here, there’s no statistical difference between secondary infection rate for child contacts compared to adult contacts.

In a study under development for publication, when we look at children 0-11 years, vs. children 12-17 years both age groups have approximately the same seroprevalence. Seroprevalence is highest amongst 0-17 year olds than all age groups.

(The rest of the video covers infection outcomes which I include for completeness).
This slide is from an early field epidemiology household transmission investigation ...This slide compares the presence of symptoms in children and adults with Covid 19 after household exposure.

All individuals less than 18 are grouped into one category. As you can see, in general, younger children and adolescents have less symptomatic illness when infected with SCV-2 than adults.

Children have more upper respiratory symptoms, largely driven by runny nose but they have significantly less lower respiratory symptoms. The same pattern with children being less symptomatic has definitely held up through several studies throughout the pandemic.

We also see children have ⬇️ hospitalization rates than adults of all ages. This graph shows the number of new C19 hospital admissions/100K stratified by age. The graph on the right shows children hospitalization rates placed on a different y axis than the graphic on the left.

(This graph was part of the presentation but somehow I failed to transcribe the audio. Apologies).

I hope the repetition of the graphs and charts wasn't confusing. I repeated them to keep them with the audio commentary and so the reader wouldn't have to keep referring backwards to the chart.
End.

Video link to Hannah Kirking's presentation which starts around minute 45:00.

Adding this entire thread from @fascinatorfun to my CDC thread. Please read. The UK is a cautionary tale of the future for the US.