If the first 3 doses of DTaP are given as TriHIBit, do they count as valid?
TriHIBit is licensed only for the 4th dose in the DTaP/Hib series. If you encounter a child who received TriHIBit for one or more of the first three doses of the series, you can count the DTaP doses as valid as long as the minimum age and minimum intervals were observed. You should revaccinate the child with single antigen Hib vaccine appropriate for the child’s age.
