Test sensitivity is secondary to frequency and turnaround time for COVID-19 screening

TLDR

The COVID‑19 pandemic has highlighted the need for robust population screening because SARS‑CoV‑2 can spread from presymptomatic, symptomatic, and asymptomatic individuals, and viral load kinetics involve an incubation period, exponential growth, peak infectiousness, and decline. The study aims to model the effectiveness of repeated population screening by evaluating test sensitivities, testing frequency, and sample‑to‑answer reporting time. The authors use a viral‑load‑kinetics‑based model to assess how these factors influence screening outcomes. Results show that screening effectiveness is driven mainly by testing frequency and rapid reporting, with only marginal gains from higher sensitivity, leading to the recommendation that screening prioritize accessibility, frequency, and turnaround time over analytical limits of detection.

Abstract

The COVID-19 pandemic has created a public health crisis. Because SARS-CoV-2 can spread from individuals with presymptomatic, symptomatic, and asymptomatic infections, the reopening of societies and the control of virus spread will be facilitated by robust population screening, for which virus testing will often be central. After infection, individuals undergo a period of incubation during which viral titers are too low to detect, followed by exponential viral growth, leading to peak viral load and infectiousness and ending with declining titers and clearance. Given the pattern of viral load kinetics, we model the effectiveness of repeated population screening considering test sensitivities, frequency, and sample-to-answer reporting time. These results demonstrate that effective screening depends largely on frequency of testing and speed of reporting and is only marginally improved by high test sensitivity. We therefore conclude that screening should prioritize accessibility, frequency, and sample-to-answer time; analytical limits of detection should be secondary.