Read on Twitter
New #COVID19 serosurvey in Italy. Report in Italian so I couldn& #39;t read it carefully. Nice thread from @stats_q with some details.
Some @nataliedean @AdamJKucharski @isabelrodbar are questioning results b/c they seem low, but deaths & IFR actually consistent w/ other data.
Thread https://twitter.com/stats_q/status/1290330189810081792">https://twitter.com/stats_q/s...
Some @nataliedean @AdamJKucharski @isabelrodbar are questioning results b/c they seem low, but deaths & IFR actually consistent w/ other data.
Thread https://twitter.com/stats_q/status/1290330189810081792">https://twitter.com/stats_q/s...
Background
Italy & Spain were worst early hit countries by COVID19 w/ reports of overloaded hospitals & at the time, huge daily deaths reaching almost 1000/day. Epidemics in US, Brazil & Mexico have sadly made these epidemics seem small in comparison.
Italy & Spain were worst early hit countries by COVID19 w/ reports of overloaded hospitals & at the time, huge daily deaths reaching almost 1000/day. Epidemics in US, Brazil & Mexico have sadly made these epidemics seem small in comparison.
An outstanding question is: what fraction of Italians were infected with the virus?
Some towns were known to be hit hard & the Lombardy region was thought to be heavily affected.
This new study suggests quite low: 2.5% for Italy & 7.5% of Lombardy had antibodies.
Some towns were known to be hit hard & the Lombardy region was thought to be heavily affected.
This new study suggests quite low: 2.5% for Italy & 7.5% of Lombardy had antibodies.
Some very smart people think these estimates are surprisingly low ( @nataliexdean @AdamJKucharski @isabelrodbar)
https://twitter.com/isabelrodbar/status/1290685761482711040
but">https://twitter.com/isabelrod... I think this is just b/c we didn& #39;t have proper scale for epidemics when they occurred in Italy.
https://twitter.com/isabelrodbar/status/1290685761482711040
but">https://twitter.com/isabelrod... I think this is just b/c we didn& #39;t have proper scale for epidemics when they occurred in Italy.
One way to assess whether seroprev is unexpectedly low is by comparing estimated fatality of COVID19 (infection fatality ratio: https://twitter.com/DiseaseEcology/status/1252844190070829056)">https://twitter.com/DiseaseEc... by age in Italy to other estimates.
Here& #39;s all rigorous age-specific IFRs I know of + crude Italy values by @stats_q. Italy IFR only high for 1 age group (70+) & could be b/c many 80+ in group (other studies split 70-9, 80-9).
(fig needs CIs)
https://doi.org/10.1016/S1473-3099(20)30243-7
https://doi.org/10.1016/S... href=" https://science.sciencemag.org/content/369/6500/208">https://science.sciencemag.org/content/3...
https://thelancet.com/pdfs/journals/laninf/PIIS1473-3099(20)30584-3.pdf">https://thelancet.com/pdfs/jour...
(fig needs CIs)
https://doi.org/10.1016/S1473-3099(20)30243-7
https://thelancet.com/pdfs/journals/laninf/PIIS1473-3099(20)30584-3.pdf">https://thelancet.com/pdfs/jour...
https://science.sciencemag.org/content/3... https://thelancet.com/pdfs/jour..." title="Here& #39;s all rigorous age-specific IFRs I know of + crude Italy values by @stats_q. Italy IFR only high for 1 age group (70+) & could be b/c many 80+ in group (other studies split 70-9, 80-9).(fig needs CIs) https://doi.org/10.1016/S... href=" https://science.sciencemag.org/content/369/6500/208">https://science.sciencemag.org/content/3... https://thelancet.com/pdfs/jour..." class="img-responsive" style="max-width:100%;"/>
Thus, the low seroprevalence in this study is actually not greatly at odds with what we know from other studies based on recorded deaths in Italy, & other estimates of age-specific IFRs.
One other point of reference is Spain which did fantastic large national survey ( https://twitter.com/DiseaseEcology/status/1280303269269532672).">https://twitter.com/DiseaseEc... There, prev was higher: 5% overall; 14.4% in some regions; 11% in Madrid. But Spain pop is younger that Italy (19.4% vs. 23% >65) & smaller (67M vs 47M), ...
so w/ slightly higher total deaths in Spain despite smaller & younger pop the serop data from Italy do not appear to be wildly low compared to Spain or IFRs.
There *may* be issues w/ Abbott serology assay missing some mild cases that @isabelrodbar & others mention in thread above but I don& #39;t think these Italy seroprev data imply that.
In conclusion, it& #39;d be best (as always) to get to read study in detail before drawing strong conclusions. Hope they make full detailed report available very soon.
Specifically, detailed data on variation in space, b/w ages, etc. would be very valuable.
Specifically, detailed data on variation in space, b/w ages, etc. would be very valuable.
Small correction: There apparently was a correction to Salje posted which decreased their IFRs by a bit (pop IFR from 0.6 to 0.5%). Here& #39;s the figure re-done w/ new corrected values.
H/T @brian_gadd
H/T @brian_gadd
Here& #39;s fig w/ error bars (except crude Italy estimates) +additional estimate of older IFR from Russell ( https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.12.2000256)">https://www.eurosurveillance.org/content/1...
