Vaccinations are such a bloody minefield. I wish I knew more about it.... I've no idea whether the authors are to be trusted or not - I like to think they are since they are vets but I'm sure we've all been fed the odd bit of crap from a vet before now...! Still, interesting reading....
http://vetmedicine.about.com/library/weekly/aa060702a.htm
http://vetmedicine.about.com/library/weekly/aa090702a.htm
http://vetmedicine.about.com/od/vaccinations/a/FALC_vacctiters.htm