Coronavirus (COVID-19): modelling the epidemic (issue no.83)

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 18th December.

2. Using data to 20th 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 20th December. R, incidence and growth rate as of 7th December.

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

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

7. Due to a larger volume of tests being processed, the turnaround time for test results has been impacted. The number of tests reported this week in Scotland has decreased since the end of last week but positivity has increased.

8. See Figure 6

9. All projections are based on current vaccine roll-out plans and efficacy assumptions. Data to 18th December.

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

11. 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.

12. 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.

13. Coverage as for week ending 20th December 2021.



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