Jenn Dowd Profile picture
May 10, 2020 18 tweets 8 min read Read on X
Some thoughts on a new pre-print from @brunoarpinoFLR @ValeriaBordone @PasqualiniMarta on empirical evidence for intergenerational contact and #COVID19 osf.io/preprints/soca…#poptwitter @oxfordemsci @melindacmills @rotondivale 1/
In our pre-print from mid-March, we hypothesized that close intergenerational ties may have helped accelerate spread of COVID-19 in Italy from Milan to the older, vulnerable population... 2/
which combined with the high % of older persons in Italy resulted in a high number of deaths. doi.org/10.1101/2020.0… 3/
As any hypothesis in an emerging situation, it’s important to test empirically as data become available. @brunoarpinoFLR & colleagues show that with aggregate level cross-country and regional data, it is difficult to find support for the hypothesis… 4/
Specifically, they find that “at the country-level higher prevalence of intergenerational co-residence and contacts is broadly positively associated with number of COVID-19 cases (per 100,000 persons), but the opposite is generally true at the sub-national level.” 5/
“While this inconsistent evidence neither demonstrates the existence nor the inexistence of a causal link b/t intergenerational relationships & the prevalence of COVID-19 cases,we warn against simplistic interpretations of the available data which suffer from many shortcomings."
"Only retrospective individual level data will provide robust evidence on the role of intergenerational ties.” Hear hear! I agree that this question is very difficult to answer with the aggregate-level data presented, for several reasons: 7/
1.) It’s more likely that high-levels of intergenerational contact *interact* with COVID-19 transmission, but are not the primary driver of cases. Original seeding and intensity of transmission is a necessary first condition. 8/
Infection seeding is partly random, but also connected to int. travel which distinguishes Milan vs Greece, for example. This is true within countries as well—the randomness of early transmission much more important for case #s than variation in intergenerational contact. 9/
Also, we hypothesized that high levels of intergenerational contact would lead to more *deaths* by hastening spread to older people. It’s not clear a priori why total *cases* would be higher or lower for intergenerational contact vs other types of social contact... 10/
...unless you assume older cases more likely to be detected. But this will vary by country and testing regime. 11/
Since the analysis here focus on cases (& cases per 100,000, which has its pros and cons as @jburnmurdoch reminds us), the lack of robust correlations within or across countries is not surprising. 12/
*Within* countries with high levels of intergenerational contact like Italy, regional variation in contact are unlikely to explain diffs in transmission. Within vs. across country variation is low, AND diffs in initial infection levels would trump these small differences. 13/
Finally- & we hope this day never comes-until the infection is very widespread it will be difficult to draw conclusions from this type of ecological analysis due to the stochastic nature of the epidemic spread AND the standard confounding problems the authors describe. 14/
This article highlights the challenge of understanding cross-country or regional differences in COVID-19 given the many factors involved, including the importance of randomness: nytimes.com/2020/05/03/wor… 15/
As @brunoarpinoFLR & colleagues emphasize, individual level data, especially following people over time is ultimately needed understand these important transmission dynamics. Some promising developments there, such as @ONS study in the UK. 16/ ons.gov.uk/surveys/inform…
We must acknowledge the high costs of family separation in instrumental and emotional support. Still, the facts of concentrated mortality at older ages requires vigilance to minimize transmission to these groups, whether that setting is families or care homes. 17/
Thanks to @brunoarpinoFLR @ValeriaBordone & @PasqualiniMarta for this important critical lens and pushing the empirical ball forward! #poptwitter #demography #epitwitter @AndreasShrugged @timriffe1 18/18

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More from @drjenndowd

Mar 20, 2021
@MariaGlymour @jimiadams Great question. We get lots of questions @DearPandemic that are VERY specific about somone's situation, so our challenge has been to convey that risk is a continuum & help people take more general principles & apply their own judgment. @lindsleininger has been great on this...
@MariaGlymour @jimiadams @DearPandemic @lindsleininger "Risk is not an on or off switch. It's more like a dimmer, it's like a dial. If your risk budget is such that you want to spend all those chips on hugging somebody as safely as you possibly can, I think that, you know, the risk reward benefit might be worth it for you...
@MariaGlymour @jimiadams @DearPandemic @lindsleininger ..."depending on the context. When I think about my own risk budget, there's three components of it: There's personal risk, how at risk of a bad outcome I am; There's interpersonal risk, so my loved ones, what's their risk level; And then there's community risk."
Read 7 tweets
Feb 20, 2021
1/ My take on why COVID-19 cases are falling. As the wise @mtosterholm has said repeatedly, we need more humility in thinking we can easily explain the epidemic's every move. slate.com/technology/202… @FutureTenseNow @Slate @DearPandemic @OxfordDemSci
2/ Remember this? Modeling humans & viruses is...hard. vox.com/future-perfect…
3/ There are several plausible hypotheses for current drops in case numbers: 1) vaccinations 2) less testing 3) behavior/policy change 4) seasonality 5) herd immunity 6) "known unknowns."
Read 16 tweets
Sep 24, 2020
1/ In this opinion for @guardian, I discuss exponential growth, natural herd immunity, and how to prioritize mitigation strategies going forward. A thread: theguardian.com/commentisfree/… @trishgreenhalgh @melindacmills @OxfordDemSci
2/ To borrow from fellow @DearPandemic Nerdy Girl @lindseyleninger, “Exponential growth sucks.” I used a different word in print but it seems a propos for twitter. This sharp upward trajectory means cases (and then hospitalizations & deaths) can quickly get out of hand.
3/ On the + side, cutting off growth sooner pays big dividends in avoided cases. Since we only measured the tip of the iceberg of cases last Spring, we are likely in a much better place despite the large # of confirmed cases. This means we still have a chance to intervene early.
Read 18 tweets
Sep 11, 2020
1/ Did the Sturgis bike rally cause 266,796 new cases of COVID-19? Probably not. Lesson- Beware viral studies that confirm your pre-existing beliefs so satisfyingly. (Long) thread: slate.com/technology/202… @FutureTenseNow @EricTopol @slate @govkristinoem @DearPandemic #Sturgis
2/ Like most people working on COVID-19, I am of the strong belief that mass gatherings during a pandemic are a bad idea. When this paper came out, the huge figures immediately hit the "I Told you So!" button in my & many people’s brains. iza.org/publications/d…
3/ The first red flag is the huge number itself-it doesn't pass the sniff test.
Read 27 tweets
Jul 16, 2020
1/ 👇What is the real #COVID19 death toll in England & Wales? In our new study led by @jm_aburto & @ridhikash07, we estimate 53,937 excess deaths in the first half of 2020, roughly 33% higher than officially reported COVID-19 deaths. bit.ly/30koOrx Image
2/ Excess deaths vary by age & sex, with males comprising 54% of excess deaths in despite being a smaller proportion of the population at the oldest ages (so males have a higher risk of dying at all ages).
3/ The largest numbers of lives lost were among the 75-85 & 85+ groups, reflecting mortality 29.1% & 36.8% above expected levels. 15-44 year olds accounted for only 290 excess deaths, 6.1% above the expected level. Image
Read 8 tweets
Jul 1, 2020
Really interesting study showing T-cell response to SARS-CoV-2 in some blood donors & exposed family members even in the absence of antibodies. I'm a bit concerned about the press release/media take that this means seroprevalence is significantly underestimated 1/
.@marcus_buggert, am I reading this figure right: 9/31 vs 4/31 blood donors had T cell but not antibody responses, & 26/28 vs 17/28 for exposed family members? How does this match claim that almost 2X as many exposed family members & donors generated T Cells but not antibodies? Image
I think this is great work & I would LOVE for immunity to be higher than current estimates. I worry about the science communication though, & think not surprisingly the headlines seem overstated: bbc.co.uk/news/health-53… 3/
Read 6 tweets

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