Scabbing on comb- what is it?

[TheWolfRaven]

Noticed this on one hen.
24 week old Australorp. Not yet laying.

Raised bump. Two noticeable ones.
Top of comb seems to be chalky white- appears flakey.

I cannot for the life of me catch this one hen- and it stresses her greatly to do so and would rather (for both our sakes) not have to unless something needed to be done.

She was vaccinated as a chick against common ailments. The other two show no signs of this and one has begun laying (third egg today).

Any clue on what this is and how to deal with it?

 

[TheWolfRaven]

Just a quick update- my chickens were vaccinated against fowl pox, so I have ruled that out.

 

[dawg53]

Just a quick update- my chickens were vaccinated against fowl pox, so I have ruled that out.

Not necessarily. Here's a link explaining vaccine failure:
http://edis.ifas.ufl.edu/vm062
Additionally the fowl pox vaccination only prevents against one strain of the virus. It's possible your hen may have a different strain, if that's what it is.