Should I Have My Chicks Vaccinated for Marek's Disease?

By orrpeople · Dec 6, 2017 · ·
  1. orrpeople
    There's that question!! It's at the end of every order for chicks purchased from a hatchery, and even from some small hobby farms. The Marek's vaccination? Should I get it? What, exactly, is it? Do my chicks really need it? Will it harm them? Why do I have to decide before I get my chicks?

    The first time I ordered chicks from a hatchery, I was already so astounded by the fact that I had to order so many chicks and pay so much for shipping, that the idea of tacking on even one more cent was just inconceivable. Granted, I was fairly new to raising chickens and didn't really even know what types of chicken diseases were "out there" in the first place! Marek's seemed like something foreign, distant, and rare. I had no idea how common and prevalent it is.

    The purpose of this article is two-fold. But first, I will tell you what it is not. It is not an in-depth article about Marek's disease. Others have done beautiful, extensive work with this topic. It is also not a "pro" or "anti" vaccinations discussion. We all must make our best, educated decisions regarding the health and well-being of our birds.

    My first goal is to shed some light on the vaccine itself; why and how it came into existence, and what makes it effective/ineffective.

    My second goal is to explain the process for administering the vaccine, as well as why it is only given to chicks.

    I would also like to achieve both of these goals using layman's terms. In other words, although the science involved is extensive and intricate, it is vitally important that anyone with a backyard flock be able to understand the topic and make an educated choice for their birds.

    In the 1920's, the poultry industry hit a large "bump" in the road...a virulent disease began to destroy large quantities of birds. It killed in a variety of different methods - but always leaving its tell-tale visceral tumors (tumors on internal organs) as a calling card. The disease, which came to be known as Marek's disease (after the man who identified it), rapidly spread world-wide on the dander (tiny skin cells) of infected birds.

    Between the 1930's and 1960's, attempts were made to breed chickens for resistance to the virus. This proved to be quite complicated due to genetic chromosome issues (inbreeding). It also opened doorways for other viruses by creating too many birds that were genetically similar.

    In the 1960's, the first vaccination for Marek's was created. Made from a Herpesvirus from turkeys, it was a groundbreaking discovery. It was the first time a vaccine effectively stemmed the development of tumors - in any species! Widely successful, it eliminated the drastic losses associated with the disease for roughly ten years.


    But viruses are living organisms that adapt to their environment in order to survive. So, despite good vaccination protocols, more Marek's cases began to occur. New vaccines were introduced; and combining vaccines was also practiced. Over the last 40+ years, the use of vaccines managed to reduce Marek's mortality by almost 99%, but the disease could not be eradicated completely.

    One of the reasons the virus continued to create complications was that the vaccine functioned not to eradicate the disease itself, but to keep the virus from killing its host. It prevented the growth of the lethal tumors formed by the Marek's virus, but did not keep chickens from "catching" the disease. Therefore, inoculated birds were still able to carry the virus, thus continuing its spread. They were, however, not dying, and the poultry industry was kept afloat as a result.

    As backyard chicken owners in 2017 (almost 2018!), we are the beneficiaries of historical vaccination protocols. Even though vaccination did not address the underlying cause of the disease, it did allow birds to live out their lives, producing offspring, and many of the vast variety of colorful breeds we know and love today.

    But, should today's backyard hobbyist have their chicks vaccinated for the disease?

    First, in order for the vaccine to have any effect on the bird's system, it must be administered before the bird is 24 hours old. Often hatcheries have the capability to give the "shot" at day 18 of incubation - while the chick is still developing in the egg. Others innoculate just-hatched chicks. The reason for this early vaccination protocol is to -effectively- "beat" the deadly virus to the punch. Once a chick is exposed to outside elements, it is, quite literally, a race as to which will take hold in their system first; the vaccine, or the virus. Chicks who have been given the vaccine must then be free from any possible exposure to the Marek's virus for 7-10 days, giving the vaccination an opportunity to bond with the bird's genome.


    As stated earlier, the Marek's vaccine is derived from the turkey form of the same type of virus (they are both Herpes viruses). It is not a chemical or artificially created substance. The vaccine has never been shown to cause Marek's in chickens, therefore, vaccinating a bird cannot infect that bird or those with whom it comes into contact. Only the Marek's virus, itself, can cause an infection. It is, however, as possible to contract the disease from a vaccinated bird as a non-vaccinated bird, as both can contract the virus.

    As other extensive articles have stated, the Marek's virus is likely found in all poultry environments. It has an extraordinary capability for dormancy. Environmental flock management factors like good hygiene and health maintenance programs; proper coop size and space; and limits on stress, prove to greatly reduce the virus' impact on backyard flocks. Therefore, it is entirely possible for a backyard hobbyist to never encounter the manifestation of the disease, and vaccination may not be necessary.

    However, poultry populations such as show stock, new imports, or birds kept in high population density conditions, will likely maintain a much higher risk for succumbing to the disease. These factors may indicate the need for vaccination.

    It is vitally important to note that poultry owners must assume their chickens carry the virus, whether vaccinated or not. Therefore, they must always endeavor to limit factors that may trigger an outbreak. The vaccine is not a foolproof "cure-all" - in fact, as the virus continues to adapt and mutate, it may become increasingly more difficult to address with the current vaccination protocol.

    Making educated choices is one of the primary duties of all backyard chicken keepers. We really do love our birds, and want only the best for them. Whether or not to have your chicks vaccinated is your choice, but unlike me - when I bought that first batch of chicks - hopefully you will know why you are - or are not - checking that Marek's vaccine box!

    "Marek's Disease: History, Actual, and Future Perspectives" (Dr. Frank Fehler)’s-disease-in-poultry

    Further recommended reading:

    A Quick and Dirty Guide to Marek's Disease: Things every chicken keeper should know.

    The Great Big Giant Marek's Disease FAQ

    Share This Article

Recent User Reviews

  1. Shadrach
    "Unbiased view of vaccination."
    5/5, 5 out of 5, reviewed Jan 3, 2019
    I liked this. It's well written, has more information in the links and most of all doesn't encourage the hysteria often associated with this disease.
    orrpeople likes this.
  2. ronott1
    "Excellant article"
    5/5, 5 out of 5, reviewed Sep 13, 2018
    Very helpful article!
  3. rjohns39
    "Great Job"
    5/5, 5 out of 5, reviewed Aug 6, 2018
    Well thought out and well written.


To make a comment simply sign up and become a member!
  1. olivigus
    I think you did an excellent job of putting this in simple but clear terms. I have a hen who developed Marek's symptoms at about 10 weeks old--paralysis, then very wobbly on her feet for weeks. I followed suggestions from some of the other articles here on BYC--fermented feed, infant vitamins, and making some accommodations so she had a platform to roost on (her feet couldn't grip the perch)--and to my surprise and delight she recovered. She is now over a year old, active and healthy. But--here's the point--she had been vaccinated at the hatchery, and I am sure that is what allowed her to live through the onset of symptoms and not develop the deadly tumors. None of my other girls have ever shown symptoms, but because I know the virus must be around, I will be certain to only get chicks that have been vaccinated when I add to the flock in the future. The information about minimizing any exposure for the first 10 days is also very helpful and important.
      crowdofmyself likes this.
  2. dehowery
    I cannot tell you how important this vaccination for chicks is! We have had to date 8 chickens/chicks die from Marek's complications. None were vaccinated all died. They all passed away around 3-4 months old. We only sent one to the lab in Alabama to be sure that was what we were dealing with. Our girls all died about the same way...First they stopped eating as vigorously as normal, then they stopped running around, then they started staring off in space and stopped eating all together and finally could not stand up, then they died. The lab results on the one we sent came back as tumor in her egg factory. She wasn't even mature enough to start laying. We are now raising a group of 11 girls that have been vaccinated they are all 4-5 months old and not one shows any sign of getting sick. So to me the 1.75 per (2 vaccines) chick was well worth it. I would like to put in a note here we had the chicks vaccinated for Marek's & Coccidiosis we lost 7 chicks in the first 2-3 days. They were just too weak. The hatchery has since posted a new policy they will not vaccinate for both you choose either marek's or cocc. This article was really RIGHT ON anyone who is thinking about raising chickens Please consider vaccinating them for Marek's it will save you allot of tears !! How could you not consider doing a simple thing like this for your Happiness & their health ???
      orrpeople likes this.
    1. orrpeople
      I do a 75%, 25% vaccinated to non-vaccinated ratio with my birds (I have a large flock) principally because I want to have "canaries in the mine"-so to speak- to let me know if there is disease in my flock; as well as protect the majority of my investment if there ever is.
    2. dehowery
      We have a broody chicken who is sitting on 5 eggs . they will hatch around the 5th. I just called and order my Marek's vaccine. I purchased it from Strombergs on line $22.00 and 11.00 for shipping.
      I believe that 33.00 is well spent in order to be sure my chicks will live past their 3rd month.
  3. ForrestGump
    Thank you for writing up the facts about Marek's vaccine. Many of us get so tired of people thinking the vaccine gives birds the disease. It does not as the vaccine is a Turkey virus that creates antibodies for the chicken form of the virus. Again, great job.
      orrpeople likes this.
    1. orrpeople
      I think the majority of the confusion arises because the term "leaky" has mistakingly been applied (even by some very well meaning and educated folks) to this vaccine when they try to describe its efficacy in eliminating the virus.
      The vaccine doesn't eliminate the virus (the cause for the commonality of the virus' presence); resulting only in the suppression of tumor growth. The term "leaky" implies "Infectious" and should not be used in connection with the MDV vaccine.
      ForrestGump likes this.
  4. CapricornFarm
    Excellent information, well written.
      orrpeople likes this.

BackYard Chickens is proudly sponsored by: