Effective contact tracing can halve mass testing frequency needed to control respiratory virus pandemics

Abstract

Mass testing is a promising strategy to control future respiratory virus pandemics, however, it is limited by the availability of testing capacity. The aim of this work is to predict the effectiveness of contact tracing when used with mass testing, and to what extent contact tracing can reduce the required number of tests. We estimate the effect of contact tracing and mass testing for controlling a variety of respiratory virus pandemics. To do this, we use a branching model with individuals whose infectiousness and probability of testing positive depend on simulated viral load trajectories. We find that the addition of contact tracing is most useful when mass testing is done frequently enough to detect most infections, but cannot be done frequently enough to reliably isolate cases before they infect others. Our results show that the addition of effective contact tracing can prevent the same number of transmissions as doubling the mass testing frequency.

Enhanced testing can substantially improve defence against several types of respiratory virus pandemic

“…72 hour) compared to the time to peak viral load, mass testing becomes substantially less useful, bringing down from R 0 = 2.5 to R e = 2.3 and 2.4 in these two examples of 61% and 34% adherence. Contact tracing will magnify the benefits of mass testing [35], and with long test delays, the indirect benefits of testing on contact quarantine become more important than the direct effects on case isolation.…”

“…For simplicity, we did not model people seeking additional testing because of symptoms, although we did model behavior modification due to symptoms even in the absence of a positive test. In a related work, we use a branching model to estimate the benefit of adding symptomatic testing and contact tracing to a mass testing policy, finding that in some scenarios adding contact tracing could allow the mass testing frequency to be halved with the same reduction in transmissions [35].…”