Effective immunity and second waves: a dynamic causal modelling study

Karl J. Friston; Thomas Parr; Peter Zeidman; Adeel Razi; Guillaume Flandin; Jean Daunizeau; Oliver J. Hulme; Alexander J. Billig; Vladimir Litvak; Cathy J. Price; Rosalyn J. Moran; Anthony Costello; Deenan Pillay; Christian Lambert

arXiv · 2006.09429

Effective immunity and second waves: a dynamic causal modelling study

Karl J. Friston·Thomas Parr·Peter Zeidman·Adeel Razi·Guillaume Flandin·Jean Daunizeau·Oliver J. Hulme·Alexander J. Billig·Vladimir Litvak·Cathy J. Price·Rosalyn J. Moran·Anthony Costello·Deenan Pillay·Christian Lambert

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Abstract

This technical report addresses a pressing issue in the trajectory of the coronavirus outbreak; namely, the rate at which effective immunity is lost following the first wave of the pandemic. This is a crucial epidemiological parameter that speaks to both the consequences of relaxing lockdown and the propensity for a second wave of infections. Using a dynamic causal model of reported cases and deaths from multiple countries, we evaluated the evidence models of progressively longer periods of immunity. The results speak to an effective population immunity of about three months that, under the model, defers any second wave for approximately six months in most countries. This may have implications for the window of opportunity for tracking and tracing, as well as for developing vaccination programmes, and other therapeutic interventions.

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Karl J. Friston, Thomas Parr, Peter Zeidman, Adeel Razi, Guillaume Flandin, Jean Daunizeau, Oliver J. Hulme, Alexander J. Billig, Vladimir Litvak, Cathy J. Price, Rosalyn J. Moran, Anthony Costello, Deenan Pillay, Christian Lambert. 2020-06-16. Effective immunity and second waves: a dynamic causal modelling study. https://arxiv.org/abs/2006.09429

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