Effective surveillance of acute COVID-19 using a cost- and labor-efficient approach: a paradigm for the longitudinal monitoring of respiratory infections in larger cohorts.

Purpose: To reduce the risk of viral transmission in a large cohort of individuals by longitudinal surveillance of COVID-19.

Methods: A cost- and labor-effective method was developed for longitudinal screening of acute COVID-19 in larger cohorts with high-level data protection. Herein, individuals would submit self-sampled tongue swabs that were analyzed for viral RNA by pooled reverse transcription-polymerase chain reaction (PCR). Results were communicated online and by telephone. Utilizing this workflow, medical and dental students at a quaternary care hospital were regularly tested between December 16, 2020, and February 17, 2023. Virus variant analysis was performed by melting curve PCR and next-generation sequencing.

Results: Our method led to a cost reduction for PCR testing that was greater than 10-fold without compromising the time to result. 3,693 individuals participated, contributing 52,993 samples. 430 cases of acute COVID-19 were detected in total. The testing behavior among participants differed from that of the general population. Periods with high numbers of newly detected cases in the study cohort coincided with high COVID-19 incidences in the public. Furthermore, one COVID-19 outbreak was observed in the cohort that was not matched by an increased incidence in the general population. Longitudinal virus variant analysis showed an overlap between variants detected in the study cohort and the public.

Conclusion: Our method enables cost-effective, longitudinal screening for COVID-19 and possibly other respiratory diseases in larger cohorts. At times of high disease burden or if public surveillance is less vigorous, this approach might be useful for the surveillance of vulnerable individuals and healthcare professionals.