M Gabriela M Gomes Profile picture
Biomathematician modeling individual variation in population dynamics
Κασσάνδρα Παρί پری Profile picture phal Profile picture Rogier v Vlissingen Profile picture Potato Of Reason Profile picture Arvo Pärt Profile picture 5 added to My Authors
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:
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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.
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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]

PLEASE READ IF YOU CAN! For more than 10 years I've been researching with collaborators (including @mlipsitch @GrahamMedley) why epidemic models tend to exaggerate epidemic sizes and overestimate intervention impacts (particularly vaccines but also NPIs):
journals.plos.org/plospathogens/…
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Dec 18, 2021
1/ Many times I have been asked why communication around herd immunity threshold (HIT) was so confusing in this pandemic. I have even been asked whether experts really understand it. Here is my answer: 2/ The concept is well understood among mathematical epidemiologists. In my view what went terribly wrong was the politicised way in which the HIT was used in this pandemic.
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Dec 17, 2021
Last year, prominent modelling groups dismissed our Covid work (known for incorporating individual variation in susceptibility and exposure, and estimating low herd immunity thresholds) by claiming our stylised contact-reduction profile (Rc) wasn't close to government NPIs.. England and Scotland (with our latest stylised Rc):
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Dec 16, 2021
No inicio da pandemia convidaram-me para integrar um daqueles grupos que fazem modelos Covid para o governo Portugues. Eu disse que nao porque queria testar um novo conceito de modelos e queria estar a vontade para fazer ciencia pura e comunicar a vontade. Comecei a ser contatada por jornalistas que me faziam perguntas as quais eu respondia avisando sempre que os meus modelos eram diferentes dos clássicos.
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Nov 28, 2021
Much is being said about Covid variants spreading sequentially faster. A couple of days ago I posted a comment on this in response to @jburnmurdoch
As we approach endemicity new variants are expected to outcompete others faster. Reason being recovered subpopulation (less immune to novel variants as long as there is some immune escape) grows as we approach endemicity increasing the benefit of novelty.
Illustration from model:
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Nov 24, 2021
Tweet que e cada vez menos novidade mas infelizmente ainda nao totalmente esclarecido principalmente em Portugal:
Levando em conta heterogeneidades realistas na susceptibilidade/exposição ao SARS-CoV-2 o limiar da imunidade de grupo para linhagens iniciais tera sido menos de 30%. Se nao tivessem emergido variantes mais transmissíveis nem vacinas (como se equacionava ha mais de 1 ano) estes limiares teriam sido ultrapassados no inverno passado. Vale o que vale mas cada vez temos mais argumentos a suportar esta afirmação.
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Sep 6, 2021
1/7
Has the herd immunity threshold (HIT) been used sensibly in the Covid19 pandemic? No! Why does that matter? 2/7
An epidemic (with several waves) may last longer than expected because: (1) it had high potential to begin with and mitigation prevented it from growing vertically so it grew horizontally (single HIT number thinking); or...
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Aug 24, 2021
Don't know how common this feeling is among mathematical epidemiologists but as someone who has worked on population dynamics of infection & immunity for 20 years I felt hopeless to see herd immunity threshold (HIT) concept degenerating in front of my eyes during pandemic. Thread 1/n
HIT is an abstract concept essential to our work but it was hijacked early in the Covid-19 pandemic and disseminated with all sorts of distortions that prevented the impact of its application by those qualified.
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May 27, 2021
Our newest #COVID19 paper (with Marcelo Ferreira @ChikinaLab @WesPegden @rjaaguas) is on medRxiv. Individual variation models applied to England and Scotland.

Frailty variation models for susceptibility and exposure to SARS-CoV-2 medrxiv.org/content/10.110… With 20% of their populations immunised by natural infection and their vulnerable vaccinated, many countries, like England and Scotland, appear to be in a comfortable position to redirect remaining vaccines to more susceptible regions.
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Dec 24, 2020
1/ I want to share a special moment with all who happen to be looking this way. This is the happiest I've been since April 27, when I posted on medRxiv a preprint with title "Individual variation in susceptibility or exposure to SARS-CoV-2 lowers the herd immunity threshold". 2/ In that preprint we study two mathematical models of the COVID-19 pandemic: one accounting for individual variation in susceptibility to infection; the other accounting for individual variation in exposure to infection (heterogeneous connectivity).
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Dec 9, 2020
TWIMC: I've been Mathematician and Mother for ~30 years (now also Grandmother) and this is what matters. I spent the last 10 years studying individual variation on characteristics that are under selection but that have no heritability repercussions in the time scale under study. In these studies I have "used" (please make a note of this word) primarily host-pathogen systems but my curiosity for completely different systems was particularly vivid last year and I was happily moving away from infectious diseases when the pandemic started.
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Oct 4, 2020
1/ Reducing transmission is not the only way of preventing deaths. From health records we can predict who is at risk of severe or fatal disease (medrxiv.org/content/10.110…, PLoS Medicine in press) and offer them shielding. 2/ Shielding was less than optimal in the first wave, because (at least in Scotland) it was implemented too late. But we are better prepared now.
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Oct 4, 2020
1/ Heterogeneous susceptibility and exposure to infection are under selection by the force of infection. Highly susceptible and highly connected individuals tend to be infected earlier and removed from the susceptible pool earlier. 2/ Mean susceptibility and mean connectivity in residual susceptible pool decrease over time lowering cumulative attack rate (CAR). Models that do not account for complete variation in those characteristics are biased towards overpredicting CAR and herd immunity threshold (HIT).
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Sep 29, 2020
1. The evidence favouring the heterogeneity model over the homogeneity model is overwhelming, whether we base this on fit penalized by complexity (DIC or similar criteria), forward predictive performance, or the Bayes factor. 2. We show that decreasing mean IFR to 0.3%, consistent with recent estimate for England, does not change fit of the model or inference that slowing and reversal of epidemic was largely attributable to build-up of herd immunity but gives a more plausible value of 15% for the HIT.
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Sep 28, 2020
Latest on individual variation in susceptibility or exposure to #SARSCoV2 and #COVID19 with Marco Colombo, Joe Mellor, Helen Colhoun and Paul McKeigue:
Trajectory of COVID-19 epidemic in Europe medrxiv.org/content/10.110… We show that relaxing the assumption of homogeneity in the modelling code released by Flaxman et al (Nature) to allow for individual variation in susceptibility or connectivity gives a model that has better fit to the data and more accurate 14-day forward prediction of mortality.
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Sep 19, 2020
@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.
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Sep 13, 2020
Whether SARS-CoV-2 has a natural herd immunity threshold (nHIT) closer to 70% or 20% is a hugely important question whose answer impacts the life of every person on Earth. I find it therefore normal that a random person forms and expresses opinions about nHIT and that some may even treat the subject just like they treat politics, religion or sports. But scientists are not random in this instance. The expectation on them is different!
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Sep 7, 2020
@joaocunhamarque @al_antdp @YouTube Tinha outros planos para este fim de dia mas troquei por assistir à sessão. Três horas bem empregues que me permitiram mais uma vez contrastar expectativas correntes com as de quem segue modelos que tratam das heterogeneidades na susceptibilidade e exposição ao virus. @joaocunhamarque @al_antdp @YouTube Quando essas heterogeneidades são tratadas por completo os modelos de transmissão passam a prever o fim da pandemia na Europa antes do início da época dos virus respiratórios sazonais.
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Aug 31, 2020
#epitwitter Core models of #COVID19 accounting for individual variation in susceptibility or exposure to infection implemented in MATLAB available from GitHub: github.com/mgmgomes1/covid These models were analysed and used to analyse the #SARSCoV2 pandemic in our 2 medRxiv preprints. First initially posted in April:
medrxiv.org/content/10.110…
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