Publication - Strategy/plan

Coronavirus (COVID-19) protective measures: indicators and data

Published: 14 May 2021
Last updated: 17 May 2021 - see all updates

Sets out the indicators to inform when and how we introduce, adapt or ease protective measures.

Coronavirus (COVID-19) protective measures: indicators and data
Indicators

Indicators

When the Strategic Framework was initially published in October 2020 introducing the five Protection Levels, a decision framework was presented which set out how data and intelligence is used to inform decisions applying the levels to local geographies. This included a basket of indicators drawing on local data.

Data related to the epidemic in Scotland were used to create five core indicators.  These were used to produce an indicator report, in conjunction with other relevant facts and circumstances, to inform discussions on the level-setting process up until December 2020.  Drawing upon clinical advice, health planning and the views of the National Incident Management Team data group, it was proposed that the indicator definitions be revised.  The core indicators and their definitions are described in Table 2 and also in more detail in the annex.

Core indicators 

Core indicators

Informing

Description

Data source

Weekly new positive cases per 100,000 people

Community transmission

Cumulative seven day count of the number of people with a first positive PCR test result divided by the area population size and multiplied by 100,000.

ECOSS

Weekly percentage of tests that are positive

Community transmission

Seven day average of the number of positive PCR tests divided by all PCR tests carried out over the past week.

ECOSS

Projected cases per 100,000 people 

Community transmission

Predicted number of PCR cases in 2 weeks’ time from modelling at local authority level.

SPI-M modellers

Current and  projected Covid hospital demand 

Healthcare capacity

Two or three-week ahead forecast  of COVID hospital demand, relative to capacity, by health board.

Scottish Government

Current and projected Covid forecast ICU demand

Healthcare capacity

Two or three week-ahead forecast of COVID ICU demand, relative to capacity, at a national level.

Scottish Government

It is important to note that the first two indicators are backward-looking – they reflect what happened in the past due to the lagged impact of past decisions and other factors.  However, when we look ahead, we are interested in what we think future changes to restrictions and other factors would do to the virus in an area: what has happened in the past is only a limited guide to what will happen in the future, particularly as new variants arise which may be more transmissible.  In other words, low case numbers now do not automatically mean that restrictions should be eased.  Instead, it is important to consider whether case numbers would remain suppressed, under the restrictions we are putting in place, if the virus was imported into an area.  This question is particularly important for areas of low incidence as travel increases and settings re-open and activities resume.  In this context forecasts play a key role – taking account of future changes in restrictions and of other relevant factors, particularly vaccination rates which would render outbreaks less harmful.

Along with the five core indicators, secondary indicators and broader considerations on health will be considered (see Table 3).  The economic and social impacts of any Level decisions will also draw on the insights of local partners and stakeholders and data such as that found on the Four Harms Dashboard. This quantitative and qualitative information will allow for transparent, reliable and consistent decision-making when setting Levels.  These indicators depend on a combination of routine data, as well as forecasts based on these data.  They might also include subjective judgements on hard-to-measure indicators such as the level of adherence with the regulations.  This is not an exhaustive or static list of all potential indicators, we will continue to draw upon the latest developments in science and technology to monitor the epidemic.

Secondary indicators

Secondary indicator

Description

Data source

Viral concentrations in units of SARS-CoV-2 million gene copies per person per day

Quantification of viral load in wastewater will give an indication of case levels in the local community.

SEPA wastewater

Prevalence and incidence of COVID-19 cases

The COVID-19 Infection Survey (CIS) is the largest regular survey of coronavirus (COVID-19) infections and antibodies, providing vital information to help the UK's response to the pandemic.

ONS

Exceedance

Exceedance is defined by Health Protection Scotland as a greater than expected rate of infection compared with the usual background.

Scottish Government ECOSS

Vaccine roll out

The proportion of the population vaccinated in an area and by age and at risk. VAXAPP and ECOSS

Community LFT testing

LFT testing to identify asymptomatic cases in an area.

NHS portal

Mortality

Number of COVID-19 attributed deaths per 100 000 population per week averaged over a seven day period.

ECOSS and NRS

Hospitalisations

Cumulative new COVID19 hospitalizations per 100 000 population averaged over a 7 day period.

RAPID

Proportion of unlinked cases amongst new cases

Defined as the proportion of cases not previously listed as contacts. It is a measure of the spread in the community beyond known clusters.  It is heavily influenced by case investigation and contact tracing capacity.

CMS and ECOSS

Testing access

Number of persons tested per 1000 population per week, averaged over a 7 day period.

ECOSS/NHS portal

Track and protect system functioning

Proportion of cases for which an investigation has been conducted within 24 hours of identification.

CMS 

Proportion of cases arising from contact lists

Proportion of cases arising from contact lists.

CMS

The aim of these indicators is to capture a reliable and robust view of current and projected local conditions in relation to health system capacity and transmission.  These will sit alongside other intelligence in informing decision making concerning the placing or lifting of restrictions. This is consistent with the approach of the WHO.  Such an approach supports transparent and consistent assessment to inform decision making that is able to respond swiftly whilst taking cognisance of wider uncertainties and science.

The decision-making for Levels allocation draws in part on numerical thresholds for a set of indicators.  The WHO thresholds that were published in the Strategic Framework Update in February 2021 remain helpful and are set out in Table 4 below.  It is important to remember that indicators and thresholds serve as one of a number of considerations, rather than being used in a rigid way.  The overall context in an area, including the delivery of the outbreak management response and the success of the vaccination programme, as well as further scientific evidence around vaccine efficacy, will always be crucial.  Situations may arise, such as the growing presence of vaccine-resistant mutations and new variants of concern both within Scotland and other countries, where the role of judgement in decision making remains central, supported by evidence, analysis, and local intelligence. 

WHO thresholds

 

 

Level 1

Level 2

Level 3

Level 4

Case incidence

New confirmed cases per 100,000 population per week averaged over a two-week period.

<20

20-<50

50-<150

150+

Test positivity

Test positivity proportion from sentinel sites averaged over a two-week period.

<2%

2%-<5%

5%-<20%

20%+

 

First published: 14 May 2021 Last updated: 17 May 2021 -