Time-variant strategies for optimizing the performance of non-pharmaceutical interventions (NPIs) in protecting lives and livelihoods during the COVID-19 pandemic

  1. Yap Wei Aun
  2. Dhesi Baha Raja

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Abstract

A stochastic Individual Contact Model (ICM) using SIR compartments allowing for time-variant parameters was used to simulate 100 non-pharmaceutical intervention (NPI) strategies and exit trajectories for a hypothetical population, and to collect epidemiological and non-epidemiological outcomes to measure the performance of these strategies over the course of a period of intervention (up to six months) for a total duration of one-year to allow the full implications of the strategy and endgame to manifest. We find that variations in the time dimension and intensity of various strategies can have vastly different performance outcomes: (i) the timing of NPIs can ‘shrink the area under the curve’ (cumulative infections) not just ‘flatten the curve’; (ii) prolonged lockdowns have diminishing margins of returns; (iii) smooth, submaximal lockdowns perform better than pulsatile lockdowns; and (iv) the efficiency of various strategies incorporating both epidemiological and non-epidemiological outcomes vary substantially. Most sobering, none of the simulated strategies allow for an ‘acceptable’ path to exit within six months due to very large gaps in health system capacity.

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    SciScore for 10.1101/2020.04.13.20063248: (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

    Software and Algorithms
    SentencesResources
    Simulations were performed using EpiModel version 1.7.5 (Jenness, SM, and Morris 2018) on R version 3.6.3 (R Core Team 2020).
    EpiModel
    suggested: (EpiModel, RRID:SCR_018539)

    Results from OddPub: Thank you for sharing your code.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    A potential caveat to this would be if certain social or economic activities price the chance, even if short, to be fully ‘active’. Under the non-epidemiological outcomes simulated in this, we include a linear measure (‘acts’ per person) which is equivocal to the difference between working at half intensity all the time vs working at full intensity half the time, and a non-linear measure (square root of ‘acts’ per person) which discounts the need to work at full intensity for at least some short periods. Low-frequency lockdowns with periods longer than two-weeks had notably poor performance, most likely due to long ‘off’ periods whereby NPI measures are removed. Submaximal lockdowns have an unstable equilibrium and can tip in either direction resulting in diminished performance. This inherent instability makes it challenging for any party to be able to hit the right spot perfectly. However, smooth submaximal and high-frequency lockdown strategies allow for easier real-time calibration of intensity during the intervention. Further analysis would be required to identify the appropriate triggers from empirical surveillance findings on the ground to inform calibration during the intervention. Submaximal lockdowns do not need to have a fixed intensity throughout and the authors conjecture that a positively skewed gentle hill with a final bump to terminate local transmissions as the population approaches the minimum level of herd immunity may be ideal. Identifying this curved bimod...

    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:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

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  2. Version published to 10.1101/2020.04.13.20063248v1 on medRxiv