ICD-10-CM > S00-T88 > T36-T50 > T50 > T50.A > T50.A2 > T50.A26 T50.A26 Underdosing of mixed bacterial vaccines without a pertussis component Non-Billable/Non-Specific Codes T50.A26A..., initial encounterT50.A26D..., subsequent encounterT50.A26S..., sequela