I just received my hatchery chicks. All 13 of them with the Marek's and Coccidosis vaccine. I am going to be buying 20 more chicks from someone local who does NOT vaccinate. They will be a few days apart, as well as two, two week old chicks included when I pick them up. My question is whether the Marek's vaccine effective in chicks over 1 day old? Like those two week old chicks. Is it safe/ effective to get them vacc'd? By the time I get these new chicks, my hatchery chicks will be about 3 weeks old.