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expert reaction to SAGE documents S1128, S1129 and S1130 looking at modelling roadmap scenarios

The latest batch of SAGE documents, giving the scientific evidence supporting the government’s response to COVID-19, have been published this afternoon.

This Roundup accompanied an SMC Briefing.


Dr Adam Kucharski, Associate Professor in Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, said:

“What happens next with COVID-19 in the UK will depend on several factors, including vaccine effectiveness and roll out over the coming months, and how quickly control measures are relaxed. This uncertainty is reflected in the different scenarios covered in the modelling analyses. Rather than focusing too much on a specific prediction, it’s therefore worth looking at the overall conclusions we can draw from such modelling.

“First, it illustrates that a sudden lifting of many measures in the near future could lead to a wave of hospitalisations larger than the one we’ve just seen. This is in part because not all groups will have been fully vaccinated yet, and in part because vaccines won’t be 100% protective – and a large epidemic could mean the remaining percentage unprotected translates into a large number of hospitalisations.

“Second, strict social distancing measures are currently doing a lot of hard work in reducing transmission in the UK, so the modelling suggests that even if a vaccine reduces transmission substantially, there could still be a resurgence if control measures are relaxed. The size and severity of the resurgence will depend on the above unknowns, highlighting the benefit of a cautious exit strategy that can respond to changes in data.  In addition, the modelling focuses on the dominant B.1.1.7 variant in the UK, rather than other variants of concern, which could also spread more easily as social distancing measures are relaxed.”


The SAGE papers:
S1128: Roadmaps for Relaxation of NPIs, modelling impact of vaccine rollout. University of Warwick

S1129: “Unlocking” Roadmap Scenarios for England v2

S1130:  SPI-M Summary of Modelling on Roadmap Scenarios

Are all under embargo until 15:30 UK time on Monday 22nd February.

Once published these papers can be found at



All our previous output on this subject can be seen at this weblink:



Declared interests

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