Temporal threshold for COVID-19 transmission used in CTQ

Determine a scientifically validated temporal proximity threshold τ for SARS‑CoV‑2 (COVID‑19) transmission to parameterize the Contact Tracing Query (CTQ), which declares two user trajectory points to be in contact when their timestamps differ by at most τ.

Background

The paper defines the Contact Tracing Query (CTQ) over user trajectories using two parameters: a spatial proximity threshold ψ and a temporal proximity threshold τ. While spatial guidance (e.g., 1–2 meters) exists from public health sources, the authors note that a definitive temporal threshold for SARS‑CoV‑2 transmission is not established.

To conduct experiments, the authors vary τ from 1 minute to 3 hours, citing a study that suggests possible upper bounds, but emphasize that the lack of authoritative temporal guidance remains an open issue. Establishing a scientifically grounded τ would strengthen the practical deployment and validity of CTQ-based systems.

References

On the other hand, there is still no authentic information on the temporal threshold for COVID-19 transmission. To the best of our knowledge, research works are still going on in this topic.

— An Efficient Index for Contact Tracing Query in a Large Spatio-Temporal Database  (2006.12812 - Ali et al., 2020) in Section 5: Experimental Evaluation, Performance Evaluation and Parameterization (paragraph below Table 1)