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

In January 2021, 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: March 2022

Since the start of the project, TestEd has tested more than 100,000 samples with more than 170 confirmed positive results. Following a change in policy in England and the UK devolved nations to limit eligibility for PCR testing in the community to those with symptoms, TestEd noticed a divergence between the reports in Scottish and UK-wide prevalence, and the magnitude and frequency of positive results in the University datasets. TestEd observed that, while UK-wide and Scottish case figures show declining or stable prevalence, University case reports have risen more than five-fold between December 2021 and February 2022. These results are most likely due to reduced community testing and, in particular, a dearth of national reporting of positive LFT results amongst the COVID-positive population. The TestEd team concluded that public health messaging need to acknowledge that reduced testing and under-reporting of positive LFTs can lead to under-estimates of community prevalence.

These results emphasise the need for continued access to high sensitivity PCR testing and other forms of surveillance, including priority for occupational or high risk settings and vulnerable populations, along with population surveillance via wastewater testing and community-based studies.

Professor Aitman
Chief Investigator of the TestEd programme