If the description is correct the study is crap. No control group at all. Some arbitrary divide between the 21st and 22d day. Trying to claim they followed more infants than they really did. I could go on.
If my math is correct, 104 seizures out of 241,011 children is 4.315155739779512e-4 or .0432%. The number is meaningless without knowing the number of unvaccinated children in the same age group who had seizures.