JMIR Publications

ABSTRACT

Background:

Monitoring the SARS-CoV-2 pandemic has so far mainly relied on passive surveillance. However, active surveillance could provide more accurate estimates of the true SARS-CoV-2 prevalence that help to forecast the evolution of the pandemic, enabling evidence-based decision-making.

Objective:

The objective of this study was to compare four different approaches of active SARS-CoV-2 surveillance, focusing on feasibility and epidemiological outcomes.

Methods:

The randomized, two-factorial, multi-arm parallel trial was conducted in 2020 in a German administrative district with approximately 700,000 inhabitants. The epidemiological outcome comprised the SARS-CoV-2 prevalence and its precision. The four study arms combined two factors: i) individuals versus households, ii) direct testing versus testing conditioned on symptom pre-screening. Individuals aged seven years and older were eligible. A total of 27,908 addresses from cluster samples of 51 municipalities were randomly allocated to the arms and 15 consecutive recruitment weekdays. Data collection and logistics were highly digitized, a study website in five languages enabled individual low-barrier registration and tracking of test results. Sample collection kits were sent by post. Participants collected a gargle sample at home and mailed it to the laboratory where it was analyzed with RT-LAMP. Samples with positive/weak RT-LAMP results were confirmed with RT-qPCR.

Results:

The response rates in the four arms varied between 34% and 41%. Altogether, 4,232 persons without pre-screening and 7,623 participating in the pre-screening provided 5,351 gargle samples, of which 5,319 (99%) could be analyzed, yielding 17 confirmed SARS-CoV-2 infections and a combined prevalence of 0.33% (95% CI [0.15%; 0.52%]) in the arms without, respectively 0.04% (95% CI [0.00%; 0.08%]) with pre-screening. Asymptomatic infections occurred in 3/11 positive cases with symptom data. The two arms without pre-screening performed best regarding effectiveness and accuracy.

Conclusions:

This study showed that self-collected gargle samples analyzed with highly sensitive RT-LAMP enable continuous active SARS-CoV-2 surveillance to detect pre- and asymptomatic cases without overburdening PCR capacities and routine diagnostic testing. Efforts to improve participation rates and to facilitate integration into the public health system can increase the potential to effectively monitor the course of the pandemic Clinical Trial: The trial was registered (30/11/2020) at the German Clinical Trials Register, registration number DRKS00023271.