Pertussis can be a very serious disease, especially for
infants. Infants (6 months of age and younger) are the
children most likely to die from this disease. Rates of
hospitalization and complications increase with decreasing age. The breathing difficulties associated with this disease can be very distressing and frightening for the
patient and his or her family.
Although adults are less likely than infants to become
seriously ill with pertussis, most adults make repeated
visits for medical care and miss work, especially when
pertussis is not initially considered as a reason for their
long-term cough. In addition, adults with pertussis
infection are a frequent source of infection to infants
with whom they have close contact.
reference : https://www.immunize.org/wp-content/uploads/catg.d/p4212.pdf