(1/4) Study of #SARSCoV2 antibody prevalence in primary and high school children from Belgium, comparing a hotspot (Alken) with a less affected region (Pelt).

When community transmission is high, young and older children are equally affected.
sciensano.be/sites/default/…
(2/4) This was a study of primary school children & those in the first 3 years of high school from two regions in Belgium.

Alken was a hotspot in the first wave (18.2 cases per 1,000 inhabitants), while Pelt was less affected (3.3/1,000). Blood was collected September - October.
(3/4) In Alken (the hotspot), antibody prevalence was similar in children (13.3%) and adolescents (15.4%).

In Pelt, 8.9% of high school children had antibodies, while none of the primary school children did.
(4/4) This suggests children and teenagers are equally susceptible.

Both are at similar risk when community transmission is high. When low, older children may be more at risk due to different contact patterns (more opportunity to socialise with peers outside school for example).

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More from @DrZoeHyde

7 Nov
Important news on the cross-reactive antibody story. Children and teenagers are more likely to have them than adults, which might explain why #COVID19 is less severe in this age group.

Children & adults are similarly likely to be infected though, so they aren’t fully protective.
While these cross-reactive antibodies might possibly explain why most children generally don’t become seriously ill with #COVID19, it doesn’t mean that herd immunity is any easier to reach.

They probably reduce disease severity at best. Children aren’t immune to infection.
There’s also the possibility that these cross-reactive antibodies have nothing to do with why children have mild illness.

Instead, they might make illness worse in people who have them. For example, through a phenomenon known as original antigenic sin.
en.m.wikipedia.org/wiki/Original_…
Read 4 tweets
31 Oct
(1/7) Important prospective study of household transmission by CDC, suggesting children and adults are similarly likely to transmit #SARSCoV2. The household secondary attack rate was at least 35%, and 18% of cases were asymptomatic.
cdc.gov/mmwr/volumes/6…
(2/7) In this study, 101 households (each with one index patient) from Tennessee and Wisconsin were followed for at least 7 days. A total of 191 household contacts of these index patients completed symptom diaries, and self-collected nasal or saliva specimens which were tested.
(3/7) None of the 191 household contacts had symptoms on the first day of the study, although some tested positive indicating they had recently been infected.

Including these contacts, the secondary attack rate was 53%. Excluding these contacts, it was 35%.
Read 7 tweets
30 Oct
(1/5) Study of #SARSCoV2 antibody prevalence in children from Bavaria, Germany, showing infections in children were 6 times higher than PCR tests suggested, and that young & older children were equally likely to be infected. Almost half were asymptomatic.
sciencedirect.com/science/articl…
(2/5) The children in this study were recruited from a representative, population-based diabetes screening study of 11,884 children.

Overall, 0.87% tested positive between April and July.

Almost half (47%) had had an asymptomatic infection.
(3/5) There was no statistically significant difference in antibody prevalence between children aged 0-6 years (0.84%) and those aged 7-18 years (0.98%).

In contrast, the results of official PCR tests had suggested young children were much less likely to be infected.
Read 5 tweets
28 Oct
My paper on #COVID19, children, and schools is now published, with new material added.

"We can no longer afford to overlook the role children play in transmission if we hope to contain the virus."

Precautions must be put in place in schools. #auspol
onlinelibrary.wiley.com/doi/full/10.56…
Important note:

The figure quoted for mortality in the paper is the case fatality rate, which is applicable to hospitalised children (a thankfully uncommon occurrence).

The infection fatality rate (mortality among all children who become infected) is probably 1000 times lower.
However, infections in children remain extremely important, because children can transmit the virus to older adults and other at-risk persons, who have far greater risk for mortality.

We will also not be able to control the pandemic unless we address transmission by children.
Read 5 tweets
27 Oct
(1/7) Report by Ministry of Health, Israel, showing children more likely to be infected than adults, are mostly asymptomatic, can be superspreaders, that school clusters spread into the community, and that school reopening accelerated the epidemic there.
gov.il/BlobFolder/rep…
(2/7) As shown in the figure below, children were more likely to test positive than adults (8% vs. 6% of all PCR tests conducted in Israel).

Children were also more likely to test positive for #SARSCoV2 antibodies than adults (7% vs. 2 - 5%).
(3/7) Most children with #COVID19 were asymptomatic (51-70%).

As shown in the figure below, children of pre-school & primary school age were more likely to be asymptomatic than older children.

The top (pink) bar indicates the proportion who were asymptomatic in each age group.
Read 8 tweets
25 Oct
(1/5) Study showing that school closures were associated with a marked reduction in the common cold in adults in the UK.

When schools reopened, rhinovirus detections surged. Physical distancing measures in schools are inadequate to prevent transmission.
thelancet.com/journals/lanre…
(2/5) In this study, patients admitted to hospital between March and September 2020 in Southampton were screened for rhinovirus.

The results were compared against data for 2019.

There was a marked decrease in rhinovirus in 2020, which was associated with school closures.
(3/5) When schools reopened, rhinovirus infections in adults increased, and became comparable to the previous year.

This suggests children are a major driver of the common cold, and that #COVID19 precautions in schools are inadequate to prevent transmission of rhinovirus.
Read 5 tweets

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