Inferring COVID-19 cases from deaths of confirmed cases

Aim: To estimate the numbers of circulating COVID-19 cases from recently reported deaths, in places where surveillance has not revealed COVID-19 infections yet. Rationale: Deaths of COVID-19 cases are indicative of wider circulation of the disease in a population. As the delay from onset to death and the case fatality ratio (CFR) have been characterised, we can infer the likely date of onset of a death, and the number of other cases (1/CFR) that had onset at the same time. From there, we use a branching process model to simulate epidemic growth, and derive estimates of the likely number of cases at present.

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