The pertussis vaccine is most effective when given to children, explains the Centers for Disease Control. The pertussis vaccine schedule recommends administering the first vaccine dose when infants are two months old, as children 1 year old or younger are the most susceptible to the disease.
The pertussis vaccine schedule includes five doses and one booster shot, explains the CDC. The first four shots are administered when the child is between 2 and 18 months old. The child should receive the final vaccine dose when she is between 4 and 6 years old, then receive the pertussis booster shot at 11 or 12 years old. Though protection against pertussis decreases after the first five shots, the risks of contracting the disease or facing complications also decline.