Martin Kulldorff on Twitter: "Hi Alasdair. The largest study is from Sweden. They never closed day-care/primary/middle schools, with zero COVID19 deaths among 1.8 million children ages 1-15. Among cases, 8 were admitted to ICU. So, low risk even with #OpenSchools at height of pandemic. https://t.co/JcHpnlIQQY… https://t.co/kyj2jTHDec"

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

We've known for some time children can get infected in mass spreading events, albeit has mostly been demonstrated in older children (see study from France) Attack rate is pretty high though! 4/13https://www.medrxiv.org/content/10.1101/2020.04.18.20071134v1 …

3 replies 11 retweets 33 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

Next an outbreak in a high school in Israel We cannot tell direction of transmission, but to me this looks like too many cases too fast to all be spread between children; I imagine multiple sources of entry Secondary schools do seem higher risk 5/13 https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.29.2001352 …

2 replies 8 retweets 41 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

Next a surprising study showing higher viral loads in younger children than adults?! At odds with previous studies showing similar, or lower VL 6/13https://jamanetwork.com/journals/jamapediatrics/fullarticle/2768952 …

3 replies 7 retweets 28 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

See here (L'Huillier) https://wwwnc.cdc.gov/eid/article/26/10/20-2403_article … Here (Jones) https://www.medrxiv.org/content/10.1101/2020.06.08.20125484v1 … Here (Kawasuji) https://www.medrxiv.org/content/10.1101/2020.06.02.20120014v1 … Confused? Me too. 7/13

1 reply 6 retweets 32 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

We already known children have transmissible virus, so this isn't new information It's nice that they targeted ONLY symptomatic individuals, so at least we have a consistent denominator Shame we still don't know how many children are asymptomatic... 8/13

2 replies 5 retweets 37 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

Next a study suggesting school closures in the USA may have prevented infections/deaths Sadly it's impossible to tell from these studies the true effect as school closures are never adopted in isolation Not sure it's helpful 9/13https://jamanetwork.com/journals/jama/fullarticle/2769034 …

4 replies 9 retweets 45 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

On which note, this study from Japan on the same topic found it made no difference Not sure we've gotten any further 10/13https://www.ijidonline.com/article/S1201-9712(20)30598-1/fulltext …

4 replies 8 retweets 37 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

Finally, 2 excellent pre-print review articles to highlight The first by @mugecevik @mlipsitch and @EdwardGoldste16 (a veritable A team of #COVID19) on age and transmission https://www.medrxiv.org/content/10.1101/2020.07.19.20157362v2 … 11/13

2 replies 21 retweets 63 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

The next also by @mugecevik et al. on viral dynamics of #COVID19 Includes interesting findings on duration of viral shedding according to age (although kids data poor, might explain apparent reduced infectivity of children despite similar VL?) 12/13 https://www.medrxiv.org/content/10.1101/2020.07.25.20162107v2 …pic.twitter.com/6n6EhxJHYJ

2 replies 9 retweets 43 likes

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Alasdair Munro‏Verified account @apsmunro 3 Aug 2020

Quick whistle stop tour there - hope to come back to some of these when (or if!) I have more time! Hoping to get the @DFTBubbles #COVID19 in children review up to date soon too! https://dontforgetthebubbles.com/evidence-summary-paediatric-covid-19-literature/ … 13/13

8 replies 10 retweets 69 likes

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Martin Kulldorff‏ @MartinKulldorff 3 Aug 2020

Replying to @apsmunro @DFTBubbles

Hi Alasdair. The largest study is from Sweden. They never closed day-care/primary/middle schools, with zero COVID19 deaths among 1.8 million children ages 1-15. Among cases, 8 were admitted to ICU. So, low risk even with #OpenSchools at height of pandemic. https://folkhalsomyndigheten.se/contentassets/c1b78bffbfde4a7899eb0d8ffdb57b09/covid-19-school-aged-children.pdf …

6:40 AM - 3 Aug 2020