A thought I've been having a lot recently - everyone says that waves 2 & 3 of COVID-19 have been markedly different from the first This is often used to support the idea that COVID-19 is getting less deadly But is it true? 1/n
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9/n If we plug these deaths and age-stratified IFRs into our equation, and assume that there is a median ~30 day lag between infection and reported death, we end up with a graph that looks like this for cases Not as different as before!pic.twitter.com/u2GPqrbnT6
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10/n Now, as I've repeatedly said, this is VERY CRUDE For example, deaths are so rare in the under-5s that it's hard to estimate any realistic number of cases in this age group. It's likely that they are underrepresented to an extent
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11/n But we can go further even than this. What if we graphed the PROPORTION of infections in each age band, inferred from deaths? It looks something like this Now the waves barely look different at allpic.twitter.com/IozFDdIxpu
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12/n In particular, if I put the two graphs side-by-side, you can see how a TINY change in the proportion in older people being infected can lead to a HUGE numerical increase in deathspic.twitter.com/QUyfQQh9z7
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13/n But broadly speaking, using this (again, VERY CRUDE) method, there appears to be little difference between waves 1 & 2 in the US It's simply that our testing changed, not that the disease itself was different
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14/n Indeed, as you can see, the FIRST wave in the US PROBABLY HAD MORE CASES THAN THE SECOND despite having fewer confirmed casespic.twitter.com/20lUU4KuOR
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15/n Interestingly, this also gives us a very crude number of total cases in the US roughly in line with
@youyanggu's modelled estimates, with about 12-15% of the country infected by late SeptemberShow this thread -
16/n Another point - people have said that this is flawed because the IFR in the second wave is less than that of the first If you reduce the IFRs in the second wave by 35%, this is what the graph looks like. Still not very different!pic.twitter.com/cuE89EVxps
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What's IFR?
Thanks. Twitter will use this to make your timeline better. UndoUndo
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Very interesting! Do you have the IFR data per age on a table? Couldn’t find it in the study and hard to get from the log chart. It would be interesting to replicate similar analysis in other countries.
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I think what you are looking for is the Metaregression Predictions tab in the Supplementary Data Spreadsheets file: https://www.medrxiv.org/highwire/filestream/98266/field_highwire_adjunct_files/0/2020.07.23.20160895-1.xlsx …
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