1. Most hatchery and feed store birds come vaccinated. From a hatchery vaccinations run about 10-20 cents a chick, depending on the hatchery. To buy a bottle for home vaccination runs 20-40 dollars for a one-time use, 1000 dose bottle or similar.
2. Bottled vaccines can be purchased online from livestock or poultry supply companies, such as Randall Burkey or Stromberg's.
3. Vaccination can be done at home; it's done at one day of age via injection in the scruff.
4. Marek's Disease is a herpes virus, and arguably one of the most common diseases affecting the domestic chicken. Once introduced it stays in a flock for life and both recovered and asymptomatic birds are carriers and capable of spreading the disease. Mild strains of Marek's (~5% or less of the flock affected) are, in some geographical areas, incredibly prevalent, appearing in nearly all flocks which are not confined indoors. Moderate and extreme forms (causing 20, 30, 40% or even higher morbidity and/or mortality) are less common. Any flock with any kind of extreme form should be put into a lifetime quarantine or destroyed, depending on the owner's wishes. Symptoms include tumors (both subcutaneous and internal; both benign and cancerous), paralysis, mishapen pupils, wasting while eating well, and lesions in the feather follicles. There is no cure or treatment for these symptoms, although some say St. John's Wort can help birds recover. Vaccines do not prevent a bird from contracting and spreading the disease, but they do prevent the bird from showing symptoms or becoming sickly (excluding the 5% of the time the vaccine fails, usually due to the bird having an inadequate immune system. Can't strengthen a wall if there's no wall there to begin with).
5. What breed are your birds? Are they breeder stock or hatchery stock? Hens and cocks cannot be vaccinated; Marek's vaccines (and some others I believe) are only effective when administered prior to 48 hours of age. Certain breeds, such as Silkies and Polish, or less resistant and should be vaccinated, especially those of hatchery lines. Other breeds, like Barred Rocks or Orpingtons, have much better resistance. Breeder lines of most birds neither are commonly vaccinated nor require it, as they are typically far more resistant than hatchery lines.
6. Chickens cannot contract the cold or flu from humans. Chickens do not experience these kinds of viruses and bacteriums like humans do; while chickens can have what appears to be a cold - coughing and sneezing that goes away after a week or so - this is always due to environmental causes. The viruses and bacteriums that cause actual colds and flus in chickens are often potentially deadly, extremely contagious, and will remain in the flock for life, with most sickened birds recovering and relapsing many times and most asymptomatic birds becoming carriers and spreaders of the disease. This is known as chronic respiratory disease.
7. The Marek's vaccine is admistered at one day of age, via an injection in the scruff. I believe most vaccines are administered similarly, although some are given at an older age. Marek's and Coccidiosis vaccines are the two most common ones; its generally not recommended other vaccines are administered, as many are live and only for use in flocks which have already contracted the disease, and if you practice good biosecurity and strict quarantine, these other vaccines should be entirely unnecessary. Marek's vaccines are recommended for most flocks since the disease transmits so easily. Coccidiosis is only necessary if the owner chooses not to feed medicated starter. If medicated starter is fed to a cocci-vaccinated bird it will null the vaccine.
8. For the Marek's vaccine, it is fine to keep a mixed flock of both vaccinated and non-vaccinated birds, provided none are under three weeks of age (it takes three weeks for the vaccine to take effect; if they happen to contract the virus prior to this age, it's effect may be void). Vaccination should not be done with gloves, as it will be hard to hold the bird.
