# Coronavirus (COVID-19): modelling the epidemic (issue no.87)

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.

## Technical Annex

Epidemiology is the study of how diseases spread within populations. One way we do this is using our best understanding of the way the infection is passed on and how it affects people who catch it to create mathematical simulations. Because people who catch Covid-19 have a relatively long period in which they can pass it on to others before they begin to have symptoms, and the majority of people infected with the virus will experience mild symptoms, this “epidemiological modelling” provides insights into the epidemic that cannot easily be measured through testing e.g. of those with symptoms, as it estimates the total number of new daily infections and infectious people, including those who are asymptomatic or have mild symptoms.

Modelling also allows us to make short-term forecasts of what may happen with a degree of uncertainty. These can be used in health care and other planning. The modelling in this research findings is undertaken using different types of data which going forward aims to both model the progress of the epidemic in Scotland and provide early indications of where any changes are taking place.

The delivery of the vaccination programme will offer protection against severe disease and death. The modelling includes assumptions about compliance with restrictions and vaccine take-up. Work is still ongoing to understand how many vaccinated people might still spread the virus if infected. As Covid-19 is a new disease there remain uncertainties associated with vaccine effectiveness. Furthermore, there is a risk that new variants emerge for which immunisation is less effective.

### Which local authorities are likely to experience high levels of Covid-19 in two weeks’ time

Table 1. Probability of local authority areas exceeding thresholds of cases per 100K (6th February to 12th February 2022).

Data to 24th January.

Probability of exceeding (cases per 100K) Local Authority (LA) 50 100 75-100% 75-100% 50-75% 25-50% 50-75% 50-75% 25-50% 15-25% 50-75% 50-75% 25-50% 0-5% 75-100% 75-100% 15-25% 0-5% 75-100% 75-100% 50-75% 15-25% 75-100% 75-100% 50-75% 5-15% 50-75% 50-75% 25-50% 5-15% 75-100% 75-100% 75-100% 25-50% 75-100% 50-75% 5-15% 0-5% 75-100% 50-75% 0-5% 0-5% 75-100% 75-100% 25-50% 5-15% 75-100% 50-75% 15-25% 0-5% 75-100% 50-75% 25-50% 5-15% 75-100% 75-100% 50-75% 25-50% 75-100% 50-75% 15-25% 5-15% 50-75% 50-75% 15-25% 5-15% 75-100% 50-75% 15-25% 5-15% 75-100% 50-75% 5-15% 0-5% 50-75% 50-75% 15-25% 5-15% 50-75% 50-75% 0-5% 0-5% 75-100% 50-75% 5-15% 0-5% 75-100% 50-75% 5-15% 0-5% 25-50% 5-15% 0-5% 0-5% 75-100% 75-100% 50-75% 15-25% 75-100% 50-75% 15-25% 0-5% 50-75% 25-50% 0-5% 0-5% 15-25% 0-5% 0-5% 0-5% 75-100% 50-75% 15-25% 0-5% 75-100% 75-100% 25-50% 5-15% 50-75% 50-75% 0-5% 0-5% 75-100% 50-75% 5-15% 0-5% 75-100% 50-75% 15-25% 5-15%

### What levels of Covid-19 are indicated by wastewater data?

Table 2 provides population weighted daily averages for normalised WW Covid-19 levels in the weeks beginning 11th January and 18th January 2022, with no estimate for error. This is given in Million gene copies per person. Coverage is given as percentage of LA inhabitants covered by a wastewater Covid-19 sampling site delivering data during this period[29].

Table 2. Average daily cases per 100k as given by WW data [30].
Local authority (LA) w/b 11th January w/b 18th January Coverage
Aberdeen City 83 54 80%
Aberdeenshire 51 48 37%
Angus 86 57 43%
Argyll and Bute 36 23 23%
City of Edinburgh 40 75 96%
Clackmannanshire 58 45 81%
Dumfries & Galloway 60 62 39%
Dundee City 103 57 100%
East Ayrshire 51 29 69%
East Dunbartonshire 72 57 99%
East Lothian 38 68 65%
East Renfrewshire 55 53 95%
Falkirk 67 61 96%
Fife 65 57 72%
Glasgow City 69 47 98%
Highland 36 34 32%
Inverclyde 50 26 98%
Midlothian 45 75 73%
Moray 122 51 14%
Na h-Eileanan Siar 0%
North Ayrshire 50 28 84%
North Lanarkshire 82 50 80%
Orkney Islands 10 10 34%
Perth and Kinross 48 32 38%
Renfrewshire 49 31 97%
Scottish Borders 38 29 48%
Shetland Islands 0%
South Ayrshire 52 28 77%
South Lanarkshire 74 47 56%
Stirling 29 23 53%
West Dunbartonshire 68 50 98%
West Lothian 49 55 72%