Our immune system

Strangely enough, I was having a conversation about shingles recently with someone who had had them.  Her medical advice was that, as long as no-one was exposed to any open blisters, she didn't need to be concerned with being contagious.  That said, I would keep my distance anyway - I'm assuming that your work colleague isn't at work.

Hi @Chev. Have you had chicken pox? 
You don't actually "catch" shingles,  but if you haven't had, or been immunised against chicken pox, you could get that. 
I think the acute immunosuppression is over reasonably quickly after your last chemo, but longer term, who knows, though I'm sure that chemo has long term effects on how our immune system functions. 
Mind you, that could also be a side effect of having had cancer. Who knows.
Take sensible precautions, don't touch your colleague,  and especially don't touch any of the blisters
Take care

I think its a bit longer than that for some people @chev  During chemo there are times when your immune system is pretty much stuffed, but it can take years to fully recover. My white cells have never come back to normal, no point in going into why that may be, but it does mean I'm more susceptible to infection and have to take that into account.
I have a flu shot every year and will look at shingles vax  in the future. MXX