The Cutter Incident

Not a claim but a documented failure. Within weeks of the Salk vaccine's licensure, batches produced by Cutter Laboratories in Berkeley were found to contain live, virulent poliovirus that the inactivation process had failed to kill. Roughly 120,000 children received the defective lots. About 40,000 developed some form of polio, 164 were left permanently paralysed and 10 died. Onward transmission from vaccinated children infected family members and communities.

The failure traced to inadequate filtration and to a licensing process that had approved manufacturing protocols without independently verifying that each producer could execute them. The problem had been flagged internally: a National Institutes of Health scientist, Bernice Eddy, had reported paralysis in monkeys given Cutter's vaccine before release, and the warning did not stop licensure. The programme was suspended nationally, the head of the NIH laboratory of biologics control and the Surgeon General both resigned, and the episode produced the modern federal system of lot-by-lot vaccine release testing.

Accounts are deliberately not collected here. This entry documents a historical case rather than a circulating remedy.

The events are not disputed by anyone, including the manufacturers and the regulator. The subsequent litigation established a liability doctrine that reshaped the vaccine industry, and the case is taught in public health schools as the founding example of why post-licensure oversight exists. It is also, straightforwardly, why a parent asking whether a vaccine batch can be defective is asking a reasonable question rather than a paranoid one.