When choosing a modified vaccination schedule (after age 2), how is immunity accomplished for DTaP if the vaccine is spaced out to one dose each 6 months ...when guidelines suggest it given every two months? Is immunity accomplished when modifying to this schedule above? What would the effective dosage be for immunity in a child age 2 and older if this is when they begin DTaP?
The eventual immunity is the same after getting the initial 3 shots, no matter when you do them (two months apart or 6 months apart). It just takes longer using the spread out way you are asking about. Also, when you've delayed DTaP until age two, I'd suggest you do the initial 3 doses in whatever timing you want, then do a 4th dose at age 4 years or later. By doing this, you don't need the 5th dose, and the immunity gained about the 4th dose (at age 4) is the same as if you'd done all 5 doses. This is possible because a delayed vaccine works a little better on a more mature immune system, so you can get by on few shots.