New findings from Swiss seroprevalence and an good opportunity to learn some more infectious disease epidemiology!
A similar prevalence in children aged 6 - 18 y (23%) than the adult population (~27%)
Lower in kids <6y (~15%) and over 65y (<15%)
What can we learn?
1/8
A similar prevalence in children aged 6 - 18 y (23%) than the adult population (~27%)
Lower in kids <6y (~15%) and over 65y (<15%)
What can we learn?
1/8
https://twitter.com/ScottGottliebMD/status/1339635334934646784
First, another lesson in age binning for kids (will we ever learn?)
6 - 18y is a weird age bin which I would not recommend
It hides big epidemiological differences
In fact, we have seen it in related data before...
2/8
6 - 18y is a weird age bin which I would not recommend
It hides big epidemiological differences
In fact, we have seen it in related data before...
2/8
The pre print of the first study from this team used age bin 5-19 y and reported no statistically different prevalence vs adults
medrxiv.org/content/10.110…
They changed for publication and found significantly lower prevalence in children <10y
thelancet.com/journals/lance…
3/8
medrxiv.org/content/10.110…
They changed for publication and found significantly lower prevalence in children <10y
thelancet.com/journals/lance…
3/8
Unsure why they would do the same thing again here, especially as a much lower prevalence in the under 6s hints it is very likely lower in the under 10's again
This is a much more important category policy wise as encompasses primary education
But we will move on...
4/8
This is a much more important category policy wise as encompasses primary education
But we will move on...
4/8
Lets just assume for now the prevalence is the same for adults and children. Would this imply children are just as susceptible as adults?
Prevalence of infection is determined by 2 things:
- Susceptibility
- Exposure
5/8
Prevalence of infection is determined by 2 things:
- Susceptibility
- Exposure
5/8
Even if my susceptibility is low, if I lick door handles on a COVID ward I'll probably get infected
If my susceptibility is high and I lock myself in a cupboard for 6 months, I won't get infected
Seroprevalence alone cannot inform us about susceptibility, but can hint...
6/8
If my susceptibility is high and I lock myself in a cupboard for 6 months, I won't get infected
Seroprevalence alone cannot inform us about susceptibility, but can hint...
6/8
Children are back at school, with many times more contacts than adults, and therefore significantly more exposure
This is precisely the scenario modelled by Zhang et al in June
-Children less susceptible
-Increased exposure evens out prevalence
science.sciencemag.org/content/368/64…
7/8
This is precisely the scenario modelled by Zhang et al in June
-Children less susceptible
-Increased exposure evens out prevalence
science.sciencemag.org/content/368/64…
7/8
In summary:
-Don't use silly age bins for children (please), split by policy implications
-Seroprevalence cannot in and of itself tell us about susceptibility
-These results are as expected if young children were less susceptible to infection (evened out by exposure)
8/8
-Don't use silly age bins for children (please), split by policy implications
-Seroprevalence cannot in and of itself tell us about susceptibility
-These results are as expected if young children were less susceptible to infection (evened out by exposure)
8/8
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