Coronavirus (COVID-19): modelling the epidemic (issue no.82)

Latest findings in modelling the COVID-19 epidemic in Scotland, both in terms of the spread of the disease through the population (epidemiological modelling) and of the demands it will place on the system, for example in terms of health care requirement.

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1. The modelling in this report uses S-gene test data to 13th December only for medium term projections, and to 14th December for Omicron doubling times.

2. Using data to 13th December 2021.

3. Particular care should be taken when interpreting this estimate as it is based on low numbers of cases, hospitalisations, or deaths and / or dominated by clustered outbreaks. It should not be treated as robust enough to inform policy decisions alone.

4. The cyan bars use Covid-19 test data and purple bars use multiple sources of data. The estimates produced by the Scottish Government are the two on the left. (Yellow uses confirmed cases from PHS and deaths from NRS; green uses wastewater data).The UKHSA consensus range is the right‑most (red). Data to 13th December. R, incidence and growth rate as of 30th November.

5. Values are included in Table 1 in the Technical Annex.

6. Public Health Scotland COVID-19 & Winter Statistical Report

7. See Figure 6

8. All projections are based on current vaccine roll-out plans and efficacy assumptions. Data to 13th December.

9. The actual positive tests are adjusted to coincide with the estimated day of infection.

10. Anomalously high values, one in Seafield (Edinburgh) in mid-February (see Issue 40), one in Dunblane in mid-June, and two in Daldowie in January, were removed. For this graph, a wastewater RNA average using the last 7-days of data is computed at every sampling date. Positivity estimates from the CIS are overlaid, with a scale chosen to approximately match the displayed peak of the survey percentage to the recent peaks in the rate of new cases.

11. The black line and red shaded area provide a smoothed curve and confidence interval for WW Covid-19 that is estimated from a generalised additive model based on a Tweedie distribution.

12. Classification of Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern (

13. Advancements in detection and interpretation practices allow us to identify when outlying results are anomalous rather than indicators of spikes in Covid-19 levels. Table 2 provides population weighted daily averages for normalised WW Covid-19 levels with the outliers removed. See Technical Annex in Issue 60 of these Research Findings for further details.

14. Coverage as for week beginning 8th December 2021.



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