Vaccine safety failures and scares

Vaccine safety decisions respond both to demonstrated harms and to fears that persist after investigation. The Cutter incident, thimerosal controversy and first rotavirus vaccine illustrate different evidence and policy problems.

The Cutter incident

The Cutter incident prompted the development of vaccine regulation in the United States. ¹ In 1955, the US government licensed Jonas Salk's polio vaccine in two hours, which some officials considered too long. ¹ Salk's vaccine was made by inactivating live poliovirus, and five companies manufactured it. ¹ Cutter Laboratories, a small company in Berkeley, California, failed during manufacture to follow Salk's protocol for killing the virus, so 200,000 people were inoculated with live virulent poliovirus; 70,000 became ill, 200 were permanently paralysed and 10 died. ¹ Cutter was held liable to compensate those harmed, but was not found negligent in production. ¹ Jurors expressed sympathy in exit interviews, viewing the available technology as inadequate for making a safe vaccine and medicine as an evolving process. ¹

Thimerosal and autism

Thimerosal is a preservative containing ethyl mercury, added to vaccines to prevent bacterial growth. ² Concern arose that infant vaccines created harmful mercury exposure, and fears rose when rates of mercury exposure and of autism in California seemed to follow similar curves over time. ² In-depth studies of neurologic disorders and autism found no link with thimerosal. ² Because the fears were so large, the government nonetheless called for thimerosal to be removed from vaccines; in 2008 multidose influenza vaccines still contained it, and more expensive single doses without it were available. ² Autism rates continued to rise in Canada and California. ^{2, 3}

The concern persisted despite the evidence: a doctor reported large increases in website inquiries whenever thimerosal and vaccine safety attracted media attention. ²

Withdrawal of the first rotavirus vaccine

A paediatric rotavirus vaccine to protect children from diarrhoea was followed by problems with fever and intussusception. ³ Doctors were asked to report adverse events, the US Centers for Disease Control and Prevention recommended postponing vaccination with the initial rhesus form of the vaccine, and vaccination stopped once true risks were identified. ³ The subsequent rotavirus vaccine consequently faced more rigorous scrutiny. ³