evidence: Controversy in the 1970s–1980s [edit]During the 1970s and 1980s, a controversy erupted related to the question of whether the whole-cell pertussis component caused permanent brain injury in rare cases, called pertussis vaccine encephalopathy. Despite this allegation, doctors recommended the vaccine due to the overwhelming public health benefit, because the claimed rate was very low (one case per 310,000 immunizations, or about 50 cases out of the 15 million immunizations each year in the United States), and the risk of death from the disease was high (pertussis killed thousands of Americans each year before the vaccine was introduced).[27] No studies showed a causal connection, and later studies showed no connection of any type between the DPT vaccine and permanent brain injury. The alleged vaccine-induced brain damage proved to be an unrelated condition, infantile epilepsy.[28] In 1990, the Journal of the American Medical Association called the connection a "myth" and "nonsense".[29] [...] It is plausible that in humans, as in nonhuman primates, asymptomatic or mildly symptomatic infections in DTaP-immunized persons may result in transmission of B. pertussis to others and may drive pertussis outbreaks.