Evaluation of Contact-Tracing Policies against the Spread of SARS-CoV-2 in Austria: An Agent-Based Simulation

Abstract

Many countries have already gone through several infection waves and mostly managed to successfully stop the exponential spread of SARS-CoV-2 through bundles of restrictive measures. Still, the danger of further waves of infections is omnipresent, and it is apparent that every containment policy must be carefully evaluated and possibly replaced by a different, less restrictive policy before it can be lifted. Tracing of contacts and consequential breaking of infection chains is a promising strategy to help contain the disease, although its precise impact on the epidemic is unknown.

Objective

In this work, we aim to quantify the impact of tracing on the containment of the disease and investigate the dynamic effects involved.

Design

We developed an agent-based model that validly depicts the spread of the disease and allows for exploratory analysis of containment policies. We applied this model to quantify the impact of different approaches of contact tracing in Austria to derive general conclusions on contract tracing.

Results

The study displays that strict tracing complements other intervention strategies. For the containment of the disease, the number of secondary infections must be reduced by about 75%. Implementing the proposed tracing strategy supplements measures worth about 5%. Evaluation of the number of preventively quarantined persons shows that household quarantine is the most effective in terms of avoided cases per quarantined person.

Limitations

The results are limited by the validity of the modeling assumptions, model parameter estimates, and the quality of the parametrization data.

Conclusions

The study shows that tracing is indeed an efficient measure to keep case numbers low but comes at a high price if the disease is not well contained. Therefore, contact tracing must be executed strictly, and adherence within the population must be held up to prevent uncontrolled outbreaks of the disease.

SciScore for 10.1101/2020.05.12.20098970: (What is this?)

Please note, not all rigor criteria are appropriate for all manuscripts.

Table 1: Rigor

NIH rigor criteria are not applicable to paper type.

Table 2: Resources

No key resources detected.

Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:

Yet, since tracing is one of the few strategies that does not impact the personal life of the population, such as closure of schools or limitation of movement, it must not be underrated. Note that all of the presented strategies are applied on top of a classical quarantine strategy in which any positively tested person is isolated. This is, essentially, the basis of any containment strategy and therefore a persistent element of the base model. Anyway, isolating persons due to a preventive quarantine measure is always related to unintended economic and sociopsychological adverse effects, which is particularly critical if the isolation turns out to be unnecessary. Consequently, any tracing measure should focus on keeping the total number of isolated persons as small as possible to reduce socioeconomic damage. The defined cost value QpIp is used to quantify the efforts of a specific tracing strategy. It relates with the direct benefit of the policy and directly correlates with the accuracy of the measure, that is the probability that a preventively isolated person is not only potentially but actually infected. Thus, the model suggests that isolation of household members is the most accurate measure and leads to the highest number of infections averted in relation to quarantined persons. Temporary closing of workplaces due to positive cases is clearly the least accurate and therefore the costliest of the modelled policies. Combining the two policies and adding additional leisure-...

Results from TrialIdentifier: No clinical trial numbers were referenced.

Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

Results from JetFighter: We did not find any issues relating to colormaps.

Results from rtransparent:

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No protocol registration statement was detected.

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