Both my primary and my pharmacist recommend two weeks between doses.
Ever curious, I asked "Why?"
The explanation was that if you have a delayed reaction, they can more clearly pinpoint the cause. Also, if you are a highly reactive individual, two at once can cause you to feel even more crummy.
Oh yes, I remember, I had to go back to the clinic over and over with one of my kids, because if she got more than one childhood immunization at a time, she had on "off the charts" immune reaction and was miserable for days.
Hope this helps.
Sue
PS I got a third dose yesterday, and so far just a really sore arm. Last dose it was headache, bodyaches, fever...