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Predictability: Can the turning point and end of an expanding epidemic be precisely forecast?

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  1. skybrian
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    Here is the abstract: From the discussion: From the conclusion:

    Here is the abstract:

    No, they can't. Exponentially growing dynamics are intrinsically unpredictable. The time at which the number of infected individuals starts decreasing cannot be reliably calculated before it is actually attained. A standard SIR model with confinement shows that infection spread is inhibited only above a threshold. Confinement induces a slow-down in the expansion phase that does not guarantee an eventual control of the epidemic. A Bayesian fit to the on-going COVID-19 pandemic in Spain shows that we can infer neither its peaking time nor whether there is a peak at all. The dispersion of possible trajectories grows extremely fast, yielding a short horizon for reliable prediction. As unpredictability is intrinsic, not due to incomplete or wrong data, our study advocates for a scenario of probabilistic forecasting.

    From the discussion:

    Confinement bends the progression curve downwards, but this bending, which can span a remarkable (and essential) lapse of time, should not be interpreted as an unequivocal sign that propagation is to be inhibited. Rather, it might represent just a transient, cross-over regime to a new diverging, exponential phase, albeit with a different coefficient.

    From the conclusion:

    SIR-like models are unable to predict with certainty; at most, they can inform on the different
    likelihood of a variety of trajectories conditional on specific measures and parameters. Uncertainties in the values of the latter prevent a unique interpretation of the data at the transient. Near the threshold separating mitigation from inhibition, the same set of observations might be compatible with either future outcome. If the aim of control protocols is to minimize the total number of infected individuals and the duration of the confinement period, it seems advisable that the strongest possible measures are applied as early as possible.

    2 votes