Enhanced Surveillance of COVID-19 in Scotland
Population-based seroprevalence surveillance 15 July 2020

About this release

This release by Public Health Scotland summarises the results and methodologies of the serology surveillance programme. The serology work stream aims to estimate the proportion of people who have antibodies to coronavirus (“seroprevalence”) in the general population of Scotland and provides the ability to detect asymptomatic and mild infections and to see if this changes over time.

The results presented in this release cover the pilot phase of the project between week commencing 20 April 2020 and week commencing 15 June 2020 (i.e. up to and including 21 June) when 4,751 samples had been received from the six participating NHS boards.

Main points

• The proportion of people who had antibodies to coronavirus is estimated to be 4.3% over the combined weeks of this pilot study.
• The proportion varied each week between 1.9% and 6.8%. Across these weeks, we can be 95% confident that the value lies between under 1% and 10%.
• The proportion among males and females showed similar patterns across the study period.
• Week to week variation varied less when compared by age, in particular among older age groups.

Background

Since week commencing 20 April, blood samples, originally collected for other clinical reasons in community healthcare settings, have been obtained from regional biochemistry laboratories in six NHS Boards: Greater Glasgow and Clyde, Grampian, Highland, Lanarkshire, Lothian, and Tayside. Approximately 500 samples are collected each week. Laboratories select specific numbers of samples by age and sex to achieve a representative sample based on the age, and sex structure of the general population in that NHS board. Samples are anonymised and sent to the Scottish Microbiology Reference Laboratory in Inverness for testing. Seroprevalence rates are adjusted for the accuracy of the antibody test.

The Centre for Virus Research (CVR) at the University of Glasgow have also been retrieving blood samples, originally collected for other diagnostic purposes in healthcare settings, from the Queen Elizabeth University Hospitals laboratory since week commencing 9 March. Samples relate to people who live in the Greater Glasgow and Clyde areas only. To date, a total of 5,955 samples have been collected by the CVR. These data are currently being analysed and used to validate our results from the regional biochemistry laboratories and will be published at the end of the project.

In total, 10,706 samples have been received to date by PHS from the six NHS Boards and the CVR.

Further information

The next release of this publication to be confirmed.