Toddler rash - vaccine reaction?

On Tuesday my 15 month old got his chicken pox vaccine.  When he got up Thursday morning he had a bit of a rash on near his knees and elbows.  On Friday,  it was all over his arms and legs and cheeks.  I talked to his doctor Friday afternoon on the phone and she felt it was probably a reaction to the vaccine, which on one hand makes sense.  However, a few of things don't seem to match up.  1.  Although some of the bumps do look like tiny water blisters, they are not red.  A few of them are crusting/scabbing over though.  2.  The info I have looked at says if there is a vaccine reaction, there will be 5 - 10 bumps - he probably has hundreds.  3.  I have read that chicken pox tends to start on the torso and then spead to the limbs - he has no bumps on his torso.
To answer any other questions, he has not been exposed to any new food, detergent, outdoor allergens, etc. and has not spent an excessive amount of time in the sun.
So, does cicken pox or a reaction to the vaccine make sense or is it possibly/probably something else?

[Bhupinder Kaur, MD]

Hello,
Without examination,confirmation of a diagnosis is tough but it indeed sounds like a reaction to the chicken pox vaccine.The other differential although less likely is molluscum contagiosum.

I would suggest a dermatologist’s evaluation as an examination along with investigations if needed may be done.

Hope it helps.Take care and pls do keep me posted on how  your child is doing or if you have any additional queries.Kind regards.