We used Footvax in 2007 - checked and sprayed feet of any suspect sheep first, then moved them to fresh grazing and moved them again after 16 days onto further fresh grazing. Haven't seen footrot or scald since - we run a closed flock and quarantine any new rams. Did see lumps on the injection site, particularly hoggetts, despite using a fresh needle each time. I would vaccinate outside fly season if doing it again, to avoid having to get the sheep up every couple of days and spray the area where they'd been rubbing the lumps against fenceposts, etc. Worth every penny to know I'll not be seeing that smelly grey mess when I turn up a foot.