An earlier version of this article cited cases for whooping cough cases from a non-governmental think tank. Those data do not coincide with figures from the government’s Centers for Disease Control. The CDC reports that 13,278 people contracted whooping cough in 2008, compared with a provisional report of 24,231 people in 2013. Broader and completed CDC data more fully demonstrate the magnitude of the growth of the disease. For example, in 2001, the CDC reported 7,580 cases, about the same as it found each year back to 1996. By 2012, the last year with completed numbers, the CDC reported 48,277 cases.