Current Controversies in the USA Regarding Vaccine Safety

Archana Chatterjee; Catherine O'Keefe

Disclosures

Expert Rev Vaccines. 2010;9(5):497-502. 

In This Article

Nervous System Disorders: Encephalopathies

The licensure of whole-cell pertussis vaccines in the 1940s marked the beginning of a dramatic decrease in the morbidity and mortality associated with Bordetella pertussis infection. Prior to the widespread use of the pertussis vaccine, hundreds of thousands of children every year contracted this debilitating respiratory infection and thousands of infants died.[36] However, despite routine use of this vaccine and, subsequently, the less reactogenic acellular pertussis vaccines, pertussis remains endemic in the USA.[37] This situation can partly be attributed to an increase in vaccine refusals as well as the modest efficacy (70–90%) of these vaccines, and an increasing adolescent and adult pool of susceptible individuals in whom immunity has waned over time.

The history of the pertussis vaccine debate dates back nearly 35 years. This controversy was first ignited by a study published in 1974 suggesting neurological complications associated with the pertussis vaccine.[38] Reports of post-vaccine febrile seizures added fuel to the fire.[39] These vaccine safety studies created significant anxiety among the general public, so that pertussis vaccine coverage plummeted in the UK from over 70% to approximately 30%.[39] Japan and Sweden also observed dramatic decreases in pertussis vaccine uptake as national mandates were lifted. The benefit of the pertussis vaccine soon became apparent as these countries quickly experienced widespread pertussis epidemics.[40] A case–control study entitled the National Childhood Encephalopathy Study (NCES) was conducted in the UK from 1976–1979, that suggested that the risk of permanent brain injury from pertussis vaccination might not be zero but was still extremely low (1 in 300,000).[41] Immunization rates began to recover after the NCES data were published. Unfortunately, the findings of the NCES were interpreted by some people as supporting a causal relationship between pertussis vaccine use and encephalopathy. Over time, this interpretation has been refuted.[42,43] In 1988, a London High Court of Justice ruling attempted to put an end to the speculation that pertussis vaccine caused serious neurological events but the damage had already been done in terms of pertussis vaccine acceptance.[39] Several well-designed studies have since been conducted that show no evidence of an association between the whole-cell diphtheria–pertussis–tetanus vaccine and encephalopathy.[44,45]

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