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Oy. Schools. This is really tough. As we debate risk/benefit, understanding whether schools are a major source of transmission to the community (and high risk people) is the billion dollar question. Thread: the science to date.
Tons of data showing kids (especially younger) disproportionately not diagnosed with #COVID19. BUT, that’s not definitive – maybe they get infected as often but don’t get symptoms. Asymptomatic disease would actually make school openings harder.
Best evidence: In Spain prevalence of antibodies in 8,243 kids<15 years was less than general pop, suggesting fewer actual infections rather than lots of asymptomatic disease (OR that they were more isolated than adults, OR that they don’t make antibodies) https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31483-5/fulltext
Let's stipulate for now that kids are genuinely less likely to be infected. Do those that are infected still spread it, though? There’s a lot of bad/inconclusive data out there. Following, some of the better evidence AGAINST spread by/among kids.
In 39 household clusters with positive kids in Switzerland, only 3 kids had symptoms before their family members, suggesting transmission overwhelmingly FROM not TO family. https://pediatrics.aappublications.org/content/early/2020/07/08/peds.2020-1576
In 15 Australian schools, 9 students/9 teachers were positive; of their 863 contacts, 0 teachers and 2 kids subsequently tested positive (1 primary school, 1 high school). But, school attendance was dropping through the period as #COVID19 fears rose. http://ncirs.org.au/sites/default/files/2020-04/NCIRS%20NSW%20Schools%20COVID_Summary_FINAL%20public_26%20April%202020.pdf
In Ireland, 3 kids and 3 teachers were positive. Only two subsequent cases were detected among 1,155 of their contacts (both non-school adults who caught it from infected teachers). https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.21.2000903
In an early outbreak in France, one positive child attended school while symptomatic; of 84 high/moderate risk contacts only 1 subsequently tested positive (the schools were closed for two weeks once initial diagnosis made). https://academic.oup.com/cid/article/doi/10.1093/cid/ciaa424/5819060
In Denmark and Finland, with low community prevalence, opening schools did not increase spread according to their governments, but *I can not find data.* However, their schools have been open since April 15 and May 14 with no increase in national cases. https://www.reuters.com/article/us-health-coronavirus-denmark-reopening/reopening-schools-in-denmark-did-not-worsen-outbreak-data-shows-idUSKBN2341N7
Note that Denmark and Finland didn't just open schools willy nilly, but put a variety of safety measures in place, and opened elementary a month before high school. https://www.brookings.edu/blog/education-plus-development/2020/07/06/reopening-the-world-reopening-schools-insights-from-denmark-and-finland/
So, there is some evidence that (younger) kids tend to catch the disease from adults rather than the reverse, and better evidence that they don’t tend to spread it a lot among other kids or contacts once infected.
But there is also evidence FOR spread by/among kids within schools; here we leave the realm of published data and move to news reports. Note that the risks here are mostly high school level.
In New Zealand, one high school developed 96 cases after a teacher tested positive. https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12340066
Israel is the most concerning example; it reopened schools May 17 with low national prevalence but has now seen major spread through schools (153 kids/25 teachers at a single middle+high school; >300 positive students/teachers to date) & worse epidemic. https://www.usnews.com/news/best-countries/articles/2020-06-24/israels-schools-struggle-with-reopening-amid-coronavirus-pandemic
So bottom line: kids don't catch COVID19 as much, don't get as sick, and don't seem to spread as much. But they CAN spread to others; and the older the kids we are talking about, the more risk there is. Elementary school likely much safer than high school.
Another good paper, this from Singapore, h/t @laxswamy: 1 12 year old, 1 preschooler, 1 teacher positive in 3 schools: no spread among 119 exposed children, but 16 staff and 11 of their household members infected by the positive teacher. https://academic.oup.com/cid/article/doi/10.1093/cid/ciaa794/5862649
More evidence that older children are more like adults in their ability to transmit to others; younger children continue to seem less likely to transmit. https://wwwnc.cdc.gov/eid/article/26/10/20-1315_article?referringSource=articleShare
Adding periodically to this thread. Here is a new report from @CDCgov about outbreak at a sleepover camp. Different than in-school transmission, but relevant to pediatric transmission. First identified case was a teenage staffer. https://twitter.com/amymaxmen/status/1289241881537392640?s=21 https://twitter.com/amymaxmen/status/1289241881537392640
The full report https://www.cdc.gov/mmwr/volumes/69/wr/mm6931e1.htm
By contrast here is some data on camps and daycares collected by @ProfEmilyOster which show many have operated without outbreaks. https://emilyoster.substack.com/p/triangulating-evidence-on-outbreaks
