In 1976, fear of an impending influenza pandemic caused public health officials to launch a vaccine program that eventually included 40 million Americans. The vaccine virus used, an H1N1 strain colloquially referred to as “swine flu” vaccine, was found in retrospective studies to be a rare cause of Guillain-Barré Syndrome (GBS), a disease characterized by ascending paralysis. Approximately, 1 of every 100,000 people inoculated with the pandemic influenza vaccine developed GBS. This unfortunate association opened the door to the notion that other influenza vaccines — or indeed any vaccine — could cause GBS.

In response to public concern about the association of vaccines and GBS, Roger Baxter and colleagues at the Kaiser Permanente Vaccine Study Center examined the relationship between vaccines and GBS in 415 patients hospitalized with the disease in Northern California between 1995 and 2006 (Baxter R, Bakshi N, Fireman B, et al. Lack of Association of Guillain-Barré Syndrome With Vaccinations. Clinical Infect Dis. 2013 Jul;57(2):197-204). The authors found that the likelihood of receiving influenza vaccine six weeks prior to the onset of GBS was indistinguishable from the likelihood of receiving the vaccine within the previous nine months. In other words, people with GBS were not more likely to have received influenza vaccine recently than they were to have received the vaccine in the distant past. The same was true for tetanus vaccine, the 23-valent pneumococcal vaccine, and for all three vaccines combined.

The authors concluded, “In this large retrospective study, we did not find evidence of an increased risk of GBS following vaccinations of any kind, including influenza vaccination.” These findings should be reassuring to patients and parents who have been particularly worried about this association.