Sep 19, 2020 9 tweets 7 min read
@PieterTrapman @mlipsitch 1/ Unclear what you mean by these numbers, but a week later I finally had a couple of hours on a Saturday to have a look. Running the models in our July preprint I am now comparing the 70% lower-risk group with the whole population. Here is what I find (explanations follow).
@PieterTrapman @mlipsitch 2/ I run each of the 3 models until the pandemic is over (one year is sufficient for these models). Then I calculate the proportion of the 70% lower-risk group that has been infected and divide by the portion of the entire population that has been infected.
@PieterTrapman @mlipsitch 3/ This metric varies wildly across models even though all assumed a gamma distribution with mean=1 and coefficient of variation estimated by fitting to first wave of confirmed cases in specific countries. I calculate HIT for each case and find this to be conserved across models.
@PieterTrapman @mlipsitch 4/ Finally I calculate relative risk between 70% lower-risk group and entire population and find lower values than those for relative infected proportions. Even though I was unclear of what you were suggesting I suspect this is the metric you were interested in.
@PieterTrapman @mlipsitch 5/ Lots to discuss here. First important to realise that the relative risk as assessed directly from risk distributions is NOT what will be observed when we look at actual cases. Here is a great Review by Odd Aalen et al on "the elusive concept of frailty" ncbi.nlm.nih.gov/pmc/articles/P…
@PieterTrapman @mlipsitch The above paper was really eye opening to me and I strongly recommend it to anyone interested in individual variation in epidemiology (whether non-communicable or infections diseases).
@PieterTrapman @mlipsitch 7/ Second, HIT is conserved across models fitted to the same data while those relative measures between 70% lower-risk group and entire population are not. So it seems a distraction that we cannot afford; the pandemic is here and we can make more productive use of our time.
@PieterTrapman @mlipsitch 8/ Third, setting susceptibilities to absolute zero doesn't seem a good idea as this leads to system degeneracy (described in the context of vaccines by myself @mlipsitch @GrahamMedley and others): journals.plos.org/plospathogens/…
@PieterTrapman @mlipsitch @GrahamMedley 9/ Finally, I think we should be more responsible and avoid going public with potentially void concerns about the work of others. It can hugely time consuming and damaging not only for the authors but for scientific progress. This is meant as a general statement.

• • •

Missing some Tweet in this thread? You can try to force a refresh

This Thread may be Removed Anytime!

Twitter may remove this content at anytime! Save it as PDF for later use!

# More from @mgmgomes1

May 16
#epitwitter Just heard from JTB that our #COVID19 paper was the most downloaded in last 90 days. I plan to spend summer developing projects that build on same concepts and methods. Happy to accommodate collaborations with those interested. Just send note.
journals.elsevier.com/journal-of-the…
Broader scope viewpoints article outlining effects and inferences of unobserved variation in disease dynamics just updated on arXiv: arxiv.org/abs/2009.01354
Selection on individual variation in susceptibility or exposure to causative factors of disease (contagious or not) introduces biases when not considered in analysis.

Common errors include the following:
Feb 18
Our first peer reviewed #COVID modelling paper has just been made available online by the grand classic Journal of Theoretical Biology 🙏authors.elsevier.com/sd/article/S00…
Others will follow shortly I believe.
2/14 Joined this platform in June 2019 to say some forms of individual variation impact epidemic dynamics hugely. Not all variation matters and explanation isn’t "nonlinearities this and that". Key process can be described linearly, intuitively, and quantifiably by inference.
3/14 When covid-19 emerged I couldn’t but apply concepts and new inference procedures to the pandemic. Also couldn’t but communicate results through this and other platforms.
This post summarises concepts, results, how they were received, and how mission has been accomplished.
Feb 15
Almost 2 years since our low-HIT (herd immunity threshold) preprint was released the paper has been peer reviewed and accepted for publication in a scientific journal (specific details soon).

The accepted version features #COVID19 in England/Scotland: medrxiv.org/content/10.110…
Following the initial preprint submitted to medRxiv in April 2020 the theory that individual variation in susceptibility and exposure (frailty variation) to infection lowers HIT and epidemic final size was featured in many news and science outlets, eg:
Jan 2
Case fatality rate em PT e UK desde que PT atingiu 85% da população vacinada com 2 doses (UK tinha 65%):
Percentagem com 2 doses em PT e UK:
Percentagem com dose de reforço em PT e UK:
Jan 2
New Year's resolution for me: No more thinking about COVID-19. Research objectives fulfilled, time for new topics.

Still polishing final writings but worthwhile thinking has been completed

Early conclusions (first released 27 April 2020) remain unchanged
medrxiv.org/content/10.110…
Two years ago had privilege to be: offered/accepting Global Talent Research Professorship at Strathclyde University @StrathMathStat; awarded Habilitation from Porto University. Both in recognition for research/teaching variation/selection in epidemiology/ecology/evolution.
Then pandemic emerged and took all time/attention. A lot has been sacrificed but I believe for good causes: research-wise immediately; policy-wise may take longer.

Happy to finally move on!
Dec 20, 2021
Dreaming about death; got up to make coffee

Then decided to write thread about what's killing me. Not depressing (on contrary). It's my duty to make the world understand this +ve thing before I die [not that I think I'll die soon; that was just in dream]