We modelled discovery since 1954 assuming a total number of species available to be discovered (the species pool) of N virus species, each discovered in any given year with probability p. The model was fitted to the data and assessed using Markov chain Monte Carlo (MCMC)-based Bayesian inference, generating distributions and credible intervals for the parameters. The model defines the expected number of discovered viruses in year t as l t ðN; pÞ Z Npð1K pÞ tK1 ;