COVID-19 testing: disparity between national and institution-based case detection

Reports of COVID-19 prevalence through national statistics, community surveys and targeted testing at places of work or study have guided national and institutional responses to the pandemic. The University of Edinburgh established a mass testing programme, TestEd, for detection of COVID-19 in asymptomatic staff and students who are studying or working on campus. The study has tested more than 100,000 samples with more than 170 confirmed positive results. Since the introduction of a change in policy in England and the UK devolved nations in early January 2022, to limit eligibility for PCR testing in the community to those with symptoms, we have noticed a divergence between the reports in Scottish and UK-wide prevalence, and the magnitude and frequency of positive results in the University datasets. While the national UK-wide and Scottish case figures show declining or stable prevalence, University case reports have risen more than five-fold since early December 2021 and continue to rise. These observations could be important in the face of future variants of concern and emphasise the need for continued access to high sensitivity PCR testing and other forms of surveillance.