Pertussis vaccine, although very effective, has the highest failure rate of any of those given routinely. It is generally believed that the vaccine is better at preventing whooping cough than preventing infection. In an ongoing study of adults with cough more than five days, pertussis was identified in a small but significant percentage. This is thought to be due to loss of vaccine-induced immunity. However, it is unclear how often this occurs in the pediatric age group.
Pertussis provides a useful paradigm for a special type of reactive airway disease.
These episodes are often precipitated by viral infections and may occur for more than a year following pertussis. Thus, whatever acute bronchitis is, it certainly is being diagnosed frequently. Children who are brought in because of cough must be evaluated to determine their management even if we have difficulty assigning a diagnosis. A cough is common to all of these children. Signs of upper respiratory infection are usually present together with transmitted rhonchi.