Coronavirus (COVID-19): state of the epidemic - 28 January 2022

Background

This report summarises the current situation of the Covid-19 epidemic in Scotland. It brings together the different sources of evidence and data about the epidemic in Scotland at this point in time, why we are at that place, and what is likely to happen next. This summarises the data up to and including 26 January 2022 on Covid-19 in Scotland. This updates the previous publication published on 21 January 2022^[1]. The information in this document helps the Scottish Government, the health service and the wider public sector respond to the epidemic and put in place what is needed to keep us safe and treat people who have the virus.

This edition of the State of the Epidemic summarises current data on Covid-19 at a national and local level, and how Scotland currently compares to the rest of the UK. It looks at the vaccination program in Scotland and its impact. Information is provided about variants of concern and what impact these may have. Bringing this information together in one place gives the opportunity to better understand the current state of the epidemic in Scotland.

Testing changes

On 5 January 2022, the Scottish Government announced that people who do not have symptoms of Covid-19 will no longer be asked to take a Polymerase Chain Reaction (PCR) test to confirm a positive Lateral Flow Device (LFD) result. Instead, anyone with a positive LFD, who do not have symptoms, should report the result online as soon as the test is done. This means that those without symptoms who previously would have taken a confirmatory PCR test, will no longer do so. As a result, these positive cases are no longer captured in the number of PCR positive cases reported by the Scottish Government and Public Health Scotland (PHS).

In order to ensure that we continue to provide the most accurate information, changes have been made to the national Covid-19 case definition to reflect this revised testing strategy. From Thursday 13 January, the Scottish Government and PHS began reporting on the number of people with a Covid-19 infection confirmed by either a PCR or first LFD positive test. These figures are classed as "experimental statistics" and may be subject to future revision as the new method for counting combined PCR and LFD tests evolves.These new experimental statistics give us a way to capture both the PCR and LFD positive cases. We need to be careful how we interpret and compare the number of cases before and after the announcement, so caution is advised.

Until 17 January 2022, an individual who tested positive by LFD and then PCR was recorded against the date of each test, resulting in patients being double-counted when the positive cases in the last seven days were calculated. From 18 January, data is reported consistently on the new method where positive cases are reported against the first positive reporting date from PCR or LFD. Any LFD positive cases that are followed by a negative PCR result within 48 hours will be denotified.

The State of the Epidemic report this week will summarise case and test data up to and including 26 January 2022. The rest of the analysis will also cover up to and including 26 January 2022 for consistency.

The State of the Epidemic Report will continue to include data from the Covid-19 Infection Survey and wastewater analysis (when available), both of which are unaffected by testing policy changes.

Everyone is being encouraged to report their LFD test data so that we can accurately understand and report the prevalence of Covid-19 and allow contacts of those with positive results to rapidly receive the correct advice to prevent onward spread. Please see the blog post for more information about the changes to reporting on Covid-19 cases.

Note on Understanding Covid-19 Test Dates

Different test dates are used when reporting cases and PCR testing data depending on the nature of the data and the use. For rapid surveillance data the reporting date has been used and is included in the figures presented in this report, whereas for detailed surveillance over time the specimen date has been used.

The reporting date is the date that new daily cases are reported by the Scottish Government and Public Health Scotland (PHS), this includes new tests reported to PHS in the previous 24 hours. The time taken for a sample to be processed and provide a result varies and does not indicate the number of samples collected or samples processed on a given day. This is however the most up to date data available.

The specimen date is the date the sample was collected from the patient. Since the time taken to test samples and report the results varies, new cases reported on a daily basis (by reporting date) may be distributed across a range of specimen dates. There is a reporting delay in testing results by specimen date, so data carried out in the most recent 2 to 3 days will be incomplete and positive tests during the most recent 10-day period may be subject to change. The specimen date data is more accurate and is recommended for interpreting data trends. Data by specimen date is more suitable for surveillance of Covid-19 over a period of time. In this report the specimen date data has a three-day lag, except for comparisons across the 4 nations which has a 5 day lag to account for different data collections across the 4 nations.