How much has the reporting of pertussis among infants increased in the U.S.?
The case-reports of pertussis among infants younger than 5 months have been increasing since the 1980s. This age group is too young to be well protected by DTaP (diphtheria and tetanus toxoids and acellular pertussis) vaccine. For example, the number of case-reports among infants younger than 5 months was about 600 per year in the early 1980s, and about 1,700 per year at the end of the 1990s. The average reported rate among infants in this age group increased more than 50% in the 1990s compared with the 1980s (the average reported rate was 89 in the 1990s per 100,000 infants). By contrast, among infants aged 5 to 11 months, there was no increase in the reported rate from the 1980s to the present. (Data from Supplementary Pertussis Surveillance System).
