I don't vaccinate but when the youngsters go to other lofts or the OLRs often the first thing they do is inject them for PMV and/or Rota.
PMV is bad news, but the Rota virus has become less of a threat here. When it first hit a few years ago it wiped out entire lofts. Now, if you get an infected stray in the shed or something some of them will be sick for a few days then bounce back. Most of them you wouldn't know they've been exposed.
