Thread by @kakape

So UK government has now published scientific evidence it has been basing its #covid19 policy decisions on. You can find it here: gov.uk/government/new…

But: "Some of the bespoke new modelling that SAGE has drawn upon to formulate its conclusions has not yet been published here. This is to allow scientists time to publish their research through the right academic channels."

This document appears to be key (cc @devisridhar): assets.publishing.service.gov.uk/government/upl…
I’ll quote what jumped out at me:

@devisridhar "SPI-M-O believes that combining all four measures [school closures, home isolation, household quarantine and social distancing], as a long-term policy, might have a similar impact to that seen in Hong Kong or mainland China –reducing the reproduction number to around 1."

@devisridhar “However, this would result in a large second epidemic once measures were lifted."

@devisridhar "Implementing a subset of measures (e.g. the first three) would be expected to have a more moderate impact – still substantially reducing peak incidence, while making a second wave of infection in Autumn less likely. This might be the preferred outcome for the NHS.”

@devisridhar "It is a political decision to consider whether it is preferable to enact stricter measures at first, lifting them gradually as required, or to start with fewer measures and add further measures if required."

@devisridhar "An additional strategy would be to apply more intense measures on those age or risk groups at most risk of experiencing severe disease ... The majority of the population would then develop immunity, hopefully preventing any second wave, while reducing pressure on the NHS."

@devisridhar That in essence seems to have been the UK policy first set out by Johnson and others. Crucially the document says about that last point of protecting vulnerable population: “However, SPI-M-O has not looked at the likely feasibility or effectiveness of such methods.”

@devisridhar I need to concentrate on something else now, but here’s what I’m struck by:
1. Surprised that combining all measures is seen as reducing R "to around 1” not clearly below given China experience (esp. if combined with aggressive testing, contact tracing)

@devisridhar 2. Argument about second wave seems to miss key point that buying time means time to prepare, get PPE for hospital staff, train on infection prevention, ramp-up testing etc., maybe even have a treatment. Weird to say “let’s take the hit now” under these circumstances.

@devisridhar 3. If there was really no additional modelling on feasibility of protecting vulnerable populations from #covid19 (and I might just not have seen that) announcing this as strategy seems incredibly callous.

@devisridhar Lots of different models and reports feeding into political decision making, of course. It will be necessary to look at everything together to understand how and why UK took certain policy decision. But certainly something that needs to be done to understand what went on.

@devisridhar For now: Good that this has been published. Wouldn’t happen in all countries, that much is for sure.