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NAChristakis's profile
Nicholas A. Christakis
Nicholas A. Christakis
Nicholas A. Christakis
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@NAChristakis

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Nicholas A. ChristakisVerified account

@NAChristakis

Sterling Professor of Social and Natural Science at Yale. Physician. Author of Apollo's Arrow; Blueprint; and Connected. Luckily wed @ErikaChristakis

Vermont, USA
humannaturelab.net
Joined August 2012

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    Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

    Let’s talk about the fact that both the attack rate and the death rate among the young is indeed very low with COVID19, unlike most prior pandemics. And let’s speculate about some of the biological reasons. 1/

    5:50 AM - 28 Mar 2020
    • 3,243 Retweets
    • 8,584 Likes
    • Leo Thanikkel #vaccine equity, we are all in this Madeleine Gardiner Christopher Marlett Jasmine Potts Debbie Eastep Glen Walker 🐲 Linda Faye 🐲 Alison Warren akiraendo
    267 replies 3,243 retweets 8,584 likes
      1. New conversation
      2. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Kids suffer so much from infectious disease around the world. It’s their leading killer (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)31593-8/fulltext … ). And so I find it haunting and sweet that they might escape the predations of COVID19. 2/pic.twitter.com/CZnqgqCmzM

        12 replies 151 retweets 773 likes
        Show this thread
      3. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Let’s define some terms. The “attack rate” is the probability that a person will come to be infected during an epidemic. Even for COVID19, it is unlikely to be >40% in the end (i.e., within the next three years); maybe just 20% of us will get it, eventually. 3/

        20 replies 92 retweets 537 likes
        Show this thread
      4. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        The “infection fatality rate” (IFR) is the probability a person will die if infected. The “(symptomatic) case fatality rate” (sCFR or CFR) is the probability of death, given that one comes to medical attention (or has symptoms). 4/

        3 replies 67 retweets 418 likes
        Show this thread
      5. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        In most respiratory disease pandemics, both the very young and the very old are likely to die, resulting in a U-shaped function with age. The 1918 pandemic famously had a W-shaped function (where working-age adults also died). COVID19 is different: curve is flat at young ages. 5/pic.twitter.com/IcTeFtswud

        3 replies 155 retweets 630 likes
        Show this thread
      6. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        From early on, it was clear COVID19 spared children. In Wuhan, no children tested positive between November 2019 and mid-January, per an early @WHO report https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf … 6/pic.twitter.com/aD3OeiOlaK

        9 replies 81 retweets 420 likes
        Show this thread
      7. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        A study of 391 cases and 1,286 close contacts in Shenzhen, China, showed that kids under 9 had an attack rate of 7.4%, similar to adults (though adults 60-69 had a higher attack rate of 15.4%). https://www.medrxiv.org/content/10.1101/2020.03.03.20028423v2.full.pdf … 7/pic.twitter.com/Fn3SgcXUrd

        6 replies 85 retweets 387 likes
        Show this thread
      8. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Overall, children were at a similar risk of infection as the adult population, though less likely to have severe symptoms, if infected. https://www.medrxiv.org/content/10.1101/2020.03.03.20028423v2.full.pdf … 8/

        3 replies 73 retweets 393 likes
        Show this thread
      9. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Another sophisticated study using multiple sources of data concluded that, compared to those aged 30–59 years, those aged <30 years and >59 years are 0.16 and 2.0 times more susceptible to symptomatic infection. https://www.nature.com/articles/s41591-020-0822-7 … via @NatureMedicine 9/pic.twitter.com/Wb5v3G4fVn

        4 replies 83 retweets 404 likes
        Show this thread
      10. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        In other good news, transmission from pregnant women to their children in utero (known as ‘vertical transmission’) seems rare for COVID-19, too. https://jamanetwork.com/journals/jama/fullarticle/2763853 … This is similar for SARS (from 2003). https://www.who.int/csr/sars/en/WHOconsensus.pdf … 10/

        5 replies 117 retweets 565 likes
        Show this thread
      11. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Nicholas A. Christakis Retweeted Nicholas A. Christakis

        Not only is the ‘attack rate’ low in children (which we will need to confirm, eventually, with 'serological' tests in large random samples, as per: https://twitter.com/NAChristakis/status/1240689935557865472?s=20 …), but the fatality rate, among those kids who do get infected, is VERY low. Yay! 11/

        Nicholas A. Christakis added,

        Nicholas A. ChristakisVerified account @NAChristakis
        Let’s talk about what happens if you get COVID19 and recover. Are you immune to the disease? How long does the immunity last? And what does that mean for your life and for the public health and economy of our society? 1/
        Show this thread
        6 replies 89 retweets 536 likes
        Show this thread
      12. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        In Wuhan, China, a very small proportion of those aged under 19 years developed severe (2.5%) or critical disease (0.2%), an early study showed. https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf … 12/

        3 replies 56 retweets 318 likes
        Show this thread
      13. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        In a study of 1,099 patients in China, via @NEJM, just 0.9 percent of confirmed cases were <14, and none died. https://www.nejm.org/doi/full/10.1056/NEJMoa2002032 … 13/pic.twitter.com/AMWR7HH5Pe

        2 replies 58 retweets 299 likes
        Show this thread
      14. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Another sophisticated study (cited above, too), using multiple sources of data https://www.nature.com/articles/s41591-020-0822-7 …, found that, if probability of developing symptoms after infection, Psym, is 0.5, the sCFR values are 0.3% (aged <30 years), 0.5% (30–59 yrs) and 2.6% (>59 yrs). 14/pic.twitter.com/cMTscd0hol

        2 replies 45 retweets 269 likes
        Show this thread
      15. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        In the Diamond Princess cruise ship, there were 3,711 people and 634 cases of COVID19 (an attack rate of 17%). Half were asymptomatic. There were just 39 people <19 years old; only 5 got infected and only 2 had symptoms; and none died. https://www.medrxiv.org/content/10.1101/2020.03.05.20031773v2 … 15/

        11 replies 85 retweets 417 likes
        Show this thread
      16. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        So, a sophisticated summary of COVID19 fatality in both symptomatic & asymptomatic patients (via https://www.medrxiv.org/content/10.1101/2020.03.04.20031104v1.full.pdf … ) is: Age 0-9: 0.0094% Age 10-19: 0.022% Age 20-29: 0.091% Age 30-39: 0.18% Age 40-49: 0.4% Age 50-59: 1.3% Age 60-69: 4.6% Age 70-79: 9.8%  Age 80+: 18%  16/pic.twitter.com/CeH8RyS8o2

        23 replies 518 retweets 1,208 likes
        Show this thread
      17. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        But the best study to date (via @AmerAcadPeds) – of 2,143 pediatric patients in China – found that, while 90% had mild or moderate illness, children <1 are indeed more likely to have critical illness, if infected. https://pediatrics.aappublications.org/content/pediatrics/early/2020/03/16/peds.2020-0702.full.pdf … 17/pic.twitter.com/MQQs7nycr6

        9 replies 92 retweets 419 likes
        Show this thread
      18. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Yet, just one child out of the 2,143 in this large Chinese pediatric cohort (who was age 14), actually died. So death among kids with COVID19 is indeed *very* rare. https://www.nytimes.com/2020/03/17/health/coronavirus-childen.html … 18/

        5 replies 79 retweets 377 likes
        Show this thread
      19. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        In the USA, as of March 18, a similar age-pattern for COVID19 was observed by the @CDCgov. Among 2,449 cases, with 123 below age 19, there were no deaths in that young age group. https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm … 19/pic.twitter.com/3O5kFdKOxX

        6 replies 84 retweets 326 likes
        Show this thread
      20. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Something similar, in terms of relatively benign course in kids, was observed in the 2003 SARS pandemic (a similar, albeit much more deadly, pathogen – CFR of ~10%), as well. In Hong Kong, no one <24 years died but >50% of patients >65 died. https://www.who.int/csr/sars/en/WHOconsensus.pdf … (Table 3) 20/

        2 replies 40 retweets 238 likes
        Show this thread
      21. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Of course, with 100,000’s of people infected in USA, there will be some cases of young people dying. And they will get news coverage. 21/

        1 reply 49 retweets 278 likes
        Show this thread
      22. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        The total US population of people <24 is about 104,000,000. With an attack rate of 7.4% and a CFR of ~0.04%, this means that about 3,000 young Americans will die of COVID19. 22/pic.twitter.com/fLkuEyWeeO

        8 replies 119 retweets 375 likes
        Show this thread
      23. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        But, even if death from COVID19 is rare for kids, they will be badly affected by our *responses* to the COVID19 pandemic -- which involve unemployment, dislocation, and fear -- as this fine essay in @TheAtlantic argues: https://www.theatlantic.com/health/archive/2020/03/what-coronavirus-will-do-kids/608608/ … Kids suffer in disasters. 23/

        4 replies 243 retweets 819 likes
        Show this thread
      24. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Nicholas A. Christakis Retweeted Nicholas A. Christakis

        To be clear, kids can indeed *transmit* the disease, which one reason (of several) that school closures are an effective tool for tamping down on the COVID19 epidemic. The little vectors. https://twitter.com/NAChristakis/status/1235204443362205699?s=20 … 24/

        Nicholas A. Christakis added,

        Nicholas A. ChristakisVerified account @NAChristakis
        Let's talk about school closures re COVID-19. It's a tough topic, scientifically and pragmatically. It's hard to estimate the benefits precisely. And closing schools can have costs, such as health care workers having to stay home, kids missing subsidized lunches, etc. 1/
        Show this thread
        5 replies 138 retweets 588 likes
        Show this thread
      25. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        There are a number of possible biological explanations for kids’ relative lack of sensitivity to COVID-19: https://www.the-scientist.com/news-opinion/possible-biological-explanations-for-kids-escape-from-covid-19-67273 … Immunologists and pediatricians have many ideas, but we just don’t know for sure yet. [thread continues...] 25/

        7 replies 140 retweets 446 likes
        Show this thread
      26. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        One idea is that children have more “adaptive” immunity (optimized for pathogens they have *not* previously seen) and that adults have more “memory” driven immunity (geared to pathogens they have indeed seen before). 26/

        7 replies 125 retweets 774 likes
        Show this thread
      27. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Another idea, via @MackayIM, is that past immunity to *other* coronaviruses might make COVID19 worse for adults by an immunological *over-reaction* to a novel coronavirus. A lot of COVID19 morbidity may be due, actually, to our bodies overreacting to the virus. 27/

        15 replies 135 retweets 793 likes
        Show this thread
      28. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Or could it be that “ACE2 receptors” (a protein on our cells that the virus binds to) are more immature in the lungs of the young, and so they provide less of a target for SARS-CoV-2 to enter our cells (I think this unlikely). 28/

        16 replies 71 retweets 466 likes
        Show this thread
      29. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Another idea relates to the aging lung environment. In order for individuals not to overreact to irritants, aged lungs counter the usual immune reaction with some tamping down of inflammation. https://www.the-scientist.com/news-opinion/possible-biological-explanations-for-kids-escape-from-covid-19-67273 … 29/

        5 replies 61 retweets 347 likes
        Show this thread
      30. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        Children may have more efficient CD4+ helper T cells which stimulate B cells to make antibodies against pathogens. Possibly, the type of T cell that dominates early in life is better at repelling SARS-CoV-2. https://www.the-scientist.com/news-opinion/possible-biological-explanations-for-kids-escape-from-covid-19-67273 … 30/

        8 replies 84 retweets 410 likes
        Show this thread
      31. Nicholas A. Christakis‏Verified account @NAChristakis 28 Mar 2020

        So there are lots of ideas about why kids might be spared. We need more SCIENCE. But this much is already clear: kids are somewhat less likely to be infected with SARS-CoV-2 and substantially less likely to get seriously ill if infected. 31/

        31 replies 89 retweets 689 likes
        Show this thread
      32. Show replies

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