Study characteristics of the published one-to-one animal transmission experiment of influenza A viruses.

†n represents the sample size, i.e. the number of pairs of a single infected animal and a susceptible animal. k represents the number of pairs with successful transmission. The numbers among control group are the highest reported frequency of infected animals in control group, while the numbers among comparison group show the lowest reported frequency of infection. ‡Judgment corresponds to the interpretation of difference in transmissibility.