Thread by @BarnardResearch

It's been a busy few days/weeks/months modelling steps 2, 3 and 4 of the #roadmap out of lockdown in England, with my #ateam @_nickdavies @markjit and John Edmunds. A 🧵 on our latest work looking at #step4 🪜👩‍💻 and a #photodump of some nice things I saw along the way

We project the dynamics of #SARSCoV2 transmission in England using an #agestructured #transmission #model which divides the population into vaccine states and disease states. The model has compartments for three #COVID19 variants (OG, #alpha and #delta) and 2 two-dose vaccines 💉

To capture changes in behaviour (➡️ the amount people mix in the model), we use historic #mobilitydata and make assumptions about what might happen to mobility when policies are implemented, e.g. #step4 🍀 We make low, medium and high assumptions to account for uncertainty... ⭐️

We also #input data on vaccine coverage by @NHSEngland region and age group over time, as well as making assumptions about #vaccineeffect against different #SARSCoV2 outcomes (infection, disease, hospitalisation, death and onward transmission) for each virus variant in the model

We use #data on #COVID19 hospital admissions, beds occupied and deaths to inform the model, as well as #SGTF (S-gene target failure) data to inform the growth of Alpha B.1.1.7 and genomic #sequencing data to inform the spread of Delta B.1.617.2.

We look at #scenarios for the potential increase in transmissibility of the #DeltaVariant as well as for levels of immune escape, including:1⃣effect of vaccines against Delta and 2⃣protection of prior infection against Delta (i.e. #crossprotection).

With these assumptions, the model projects the effect on transmission of different #policyoptions with low, medium and high mobility to the end of October 2021. Pictured: projection assumes 50% increased transmissibility and low immune escape for #Delta + #step4 on 21st June

We can also look at the effects of different policy options (e.g. 2-week, 5-week delay to #step4) for a given scenario. Pictured: assuming a 70% increase in transmissibility of #Delta relative to #Alpha and medium immune escape, with different policies investigated...

You can see the full report here, with all the assumptions and scenarios gov.uk/government/pub…

You can read the SPI-M-O summary paper here, along with reports from the brilliant teams at the University of Warwick @warwickuni and Imperial College London @imperialcollege gov.uk/government/pub…

And to end, an #honorarymention for the seagull which joined me during my Zoom meeting with @_nickdavies today