Marek's vaccine not working????

[seminolewind]

I vaccinated my group of 7 at one day old. Three weeks later I vaccinated them again, plus vaccinated another group of 5 at one day old.
The first group was quarantined for 8 weeks. , only to die from Marek's, or some infection that was opportunistic. The 2 survivors, one a skinny roo, the other went through paralysis and wasting, recovered (!) and 6 weeks later was put out with the chickens.

The other 5 are fine, they are 3 weeks younger and only got the one time vaccine.

I just don't understand. 7 were vaccinated for Marek's and I have 1 left that was unaffected.

5 died , it appears to be from a massive bleeding caused by coccidiosis that had no symptoms up until they died (hours before). If they were vaccinated , why would they be weak enough to die from coccidiosis? The last few would not eat.

Has anyone else had a number of chicks die from Marek's or coccidiosis even tho they were vaccinated for Marek's and on medicated feed?

 

[JerseyGiantfolk]

Yes. You are not the only one. I bought my chicks from SandHill, 7 Jersey Giants and 6 Dorkings.

Vaccinated them all because Marek's will usually happen in crowded chick batches, then 3 weeks later I had 3 JG's in my room dying from Marek's. (Turns out 2 of the Jersey Giants were a Australorp and Minorca)

The Dorkings never got Marek's. Even the one I forgot to vaccinate.
But 3 out of 6 Jersey Giants got Marek's, then another one had an internal injury from the Dorkings, and the last one got loose and got in a fight with another roo.

So now I just have 1 surviving JG.

So I started doing just the same breed or in 3-6 batches.

Has anyone else had a number of chicks die from Marek's or coccidiosis even tho they were vaccinated for Marek's and on medicated feed?