SPI-M-O: Consensus statement on COVID-19, 12 August 2020
Consensus statement from the Scientific Pandemic Influenza Group on Modelling, Operational sub-group (SPI-M-O) for the Scientific Advisory Group for Emergencies (SAGE).
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Consensus statement from SPI-M-O on COVID-19. It was considered at SAGE 51 on 13 August 2020.
This paper contains estimates of the reproduction number (R) and growth rate for the UK, 4 nations and NHS England (NHSE) regions. The values are shown as a range; the most likely true values are somewhere towards the middle of this range.
Estimates of R and growth rates for Scotland, Wales, Northern Ireland and NHSE regions are subject to greater uncertainty given the lower number of cases and increased variation.
When the number of cases falls to low levels and/or there is a high degree of variability in transmission across a region, then estimates of R and the growth rate become insufficiently robust to inform policy decisions.
When case numbers are low, fluctuations in the data can have a significant impact on the R and growth rate estimates. Furthermore, when there is a significant amount of variability across a region, for example due to a local outbreak, then a single average value doesn’t accurately reflect the way infections are changing throughout the region.
Different modelling groups use different data sources to estimate these values using mathematical models that simulate the spread of infections. Some may even use all these sources of information to adjust their models to better reflect the real-world situation. There is uncertainty in all these data sources, which is why estimates can vary between different models, and why we do not rely on one model; evidence from several models is considered, discussed, combined, and the growth rate and R are then presented as ranges.
See the latest R number and growth rates in the UK.
This paper also includes estimates of the change in pillar 2 test positivity in England. Please note that trends in this data are difficult to interpret due to changes in testing behaviour and testing strategies, particularly in areas of local intervention where testing volumes have increased.
We cannot currently tell how much of the estimated change in pillar 2 positivity represents a true change in the number of infections, and how much arises from changes in targeting of pillar 2 testing towards (or away from) people who are infected, for example populations with higher or lower prevalence.
It should be viewed in context: the paper was the best assessment of the evidence at the time of writing. The picture is developing rapidly and, as new evidence or data emerges, SAGE updates its advice accordingly.
Therefore, some of the information in this paper may have been superseded and the author’s opinion or conclusion may since have developed.