Risk assessment of novel coronavirus COVID-19 outbreaks outside China

Peter Boldog; Tamas Tekeli; Zsolt Vizi; Attila Denes; Ferenc Bartha; Gergely Rost

Each imported case that passes the entry screening and mixes into the local population can potentially start an outbreak, which we model by a Galton-Watson branching process with negative binomial offspring distribution with dispersion parameter k = 0.64 [19, 20] and expectation R loc , where R loc is the local reproduction number of the infection in a given country. Each branch has extinction probability z, which is the unique solution of the equation z = g(z) on the interval (0, 1), where g is the generating function of the offspring distribution (see [34] ). The process dies out if all the branches die out; thus, we estimate the risk of a major local outbreak from importation as 1 − z i , where i cases were imported.