Importation data for admin units in admin_units_seasonal
importationsA list of length 18
importations: A list of length 18, with each list representing a year. In each
year is then a further 2 lists which are:
incidence: Proportions of incidence that originated from other admin units, i.e. individuals in admin i that moved to admin j and then returned with an infection acquired while in admin j.
mosquitoFOI: Proportion of the force of infection towards mosquitoes that originated from outside admin units, i.e. the proportion of mosquitoes that are infected from infected individuals who travelled from admin j into admin i.