I have ordered my hens from McMurray and Ideal with a couple of drop offs that have been added in the past few years. I hatched out 3 Mille Fleur on 8/21. Do they need to be vaccinated and if so is it to late? I would hate to lose them to Mareks or something as adults. The oldest in my flock is hens in my flock are 4 the youngest are 10 weeks and 8 weeks.