Thread by @phenomstruck

Have we misjudged the role of children in spreading #COVID19?
COVID19 research in to kid, especially younger ones, is not perfect. It has gaps, it is evolving and we are learning more by the day.
A short summary of evolving role of children 👇
cmaj.ca/content/192/38…

Statement from Ontario’s science advisory table:

- Kids may play a bigger role in the spread of #SARSCoV2 than initially suspected.

- Early suggestions that children are considerably less important drivers of transmission are not confirmed by more recent research.

Children less susceptible?
1. Contact tracing studies reported that children<10 years old are less likely to test positive.

Limitations: Studies underestimate infection rate in children if infected children are more likely to be asymptomatic than infected adults.

Children less likely to have #SARSCoV2 antibodies?

1. Seroprevalence studies found young children less likely to have antibodies.

Limitations: Studies mostly conducted when schools were closed, therefore children were likely to have fewer social contacts.

Potential lower susceptibility of younger children:
- Due to lower density of ACE2, receptor used by virus to infect cells.
Limitation: If children have more social contacts/react differently to interventions, this could offset potential biological advantage offered by low ACE2.

References:
Contact tracing studies- doi.org/10.1126/scienc…
doi.org/10.3201/eid261…
Seroprevalence studies-
doi.org/10.1016/S0140-…
doi.org/10.1016/S0140-…
Biological advantage/ACE2 studies-
doi.org/10.1038/s41591…
doi.org/10.1371/journa…

Have we underestimated the role of children?

Viral RNA studies showed RNA levels in swabs from children and adolescents with #COVID19 were similar to those in adults with COVID-19, and infectious SARS-CoV-2 was detected in children of all ages.

Viral outbreak evidence:
An outbreak study in attendees of a youth
camp found younger children were as likely as older attendees to be infected with SARS-CoV-2. This suggests that young children can have attack rates
similar to those of older children, adolescents and adults.

References:
Viral RNA studies-
doi.org/10.1016/j.jped…
doi.org/10.1101/2020.0…
doi.org/10.1001/
wwwnc.cdc.gov/eid/article/26…
Outbreak study-
doi.org/10.15585/mmwr.…

Interpretation (1/2):

- Children could play a relevant role in transmission; school closures may have been important contributors to the containment of pandemic.

- Public health interventions could be as relevant and impactful to control transmission in children as in adults.

Interpretation (2/2)

- It appears important to include children as part of any surveillance, testing and control strategy, while bearing in
mind that children are more likely than adults to remain asymptomatic after SARSCoV-2 infection.

Statement on opening schools (1/2):

- Some European countries (#Denmark) have demonstrated that reopening schools can be safe, “provided that local transmission is low and appropriate measures are in place,” such as reduced class sizes and well-ventilated classrooms.

Statement on opening schools (2/2):

- Reopening without such measures “could be associated with a higher number of school outbreaks,” as seen in Israel.

- "Important thing is not to panic but take it seriously,”

“There will be outbreaks in schools, so the more we keep class bubbles relatively small and isolated from each other, the better we will be able to shut down individual classes instead of having to close entire schools.”
Quick overview from the report:

Finally:
Most of these studies have caveats, gaps and blind spots. Associating presented in these studies cannot be inferred as causality.

But:
It does point towards a trend and an evolving understanding of role of children in transmission.

covid19-sciencetable.ca/wp-content/upl…

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